<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>060500 - Disclosure - Inventories</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode /><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>c20130401to20130630</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0000890846</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2013-04-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-06-30T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="3 Months Ended" /><Label Key="Calendar" Id="1" Label="Jun. 30, 2013" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>1</Level><ElementName>us-gaap_InventoryDisclosureAbstract</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Inventories [Abstract]</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_InventoryDisclosureTextBlock</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>verboseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="c20130401to20130630" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div style="font-family: 'Times New Roman', Times, serif; font-size: 10pt;"&gt;&lt;div style="text-align: justify; font-family: Times New Roman; color: #000000; font-size: 10pt; font-weight: bold;"&gt;5. Inventories&lt;/div&gt;&lt;div style="text-align: left;"&gt;&lt;!--Anchor--&gt;&lt;!--Anchor--&gt;&lt;!--Anchor--&gt;&lt;br /&gt;&lt;/div&gt;&lt;div style="text-align: left; font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;Inventories are stated at the lower of cost (first-in, first-out method) or market (net realizable value). Inventories consist of the following:&lt;/div&gt;&lt;table cellpadding="0" cellspacing="0" style="width: 100%; font-family: 'Times New Roman', Times, serif; font-size: 10pt;"&gt;&lt;tr&gt;&lt;td valign="bottom" style="vertical-align: bottom;"&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="vertical-align: bottom;"&gt;&amp;#160;&lt;/td&gt;&lt;td colspan="2" valign="bottom" style="vertical-align: bottom;"&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; vertical-align: bottom;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="vertical-align: bottom;"&gt;&amp;#160;&lt;/td&gt;&lt;td colspan="2" valign="bottom" style="vertical-align: bottom;"&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; vertical-align: bottom;"&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td valign="bottom" style="padding-bottom: 2px; vertical-align: top;"&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="padding-bottom: 2px; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td colspan="2" valign="bottom" style="border-bottom: #000000 2px solid; vertical-align: top;"&gt;&lt;div style="text-align: right; font-family: Times New Roman; color: #000000; font-size: 10pt; font-weight: bold;"&gt;June 30, 2013&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; padding-bottom: 2px; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="padding-bottom: 2px; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td colspan="2" valign="bottom" style="border-bottom: #000000 2px solid; vertical-align: top;"&gt;&lt;div style="text-align: right; font-family: Times New Roman; color: #000000; font-size: 10pt; font-weight: bold;"&gt;March 31, 2013&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; padding-bottom: 2px; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td valign="bottom" style="vertical-align: top;"&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td colspan="2" valign="bottom" style="vertical-align: top;"&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td colspan="2" valign="bottom" style="vertical-align: top;"&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td valign="bottom" style="background-color: #cceeff; width: 76%; vertical-align: top;"&gt;&lt;div style="text-align: left; font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;Raw materials&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;$&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="text-align: right; background-color: #cceeff; width: 9%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;156,000&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;$&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="text-align: right; background-color: #cceeff; width: 9%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;219,000&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td valign="bottom" style="background-color: #ffffff; width: 76%; vertical-align: top;"&gt;&lt;div style="text-align: left; font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;Work-in-process&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: left; background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: right; background-color: #ffffff; width: 9%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;29,000&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: left; background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: right; background-color: #ffffff; width: 9%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;21,000&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td valign="bottom" style="background-color: #cceeff; width: 76%; vertical-align: top;"&gt;&lt;div style="text-align: left; font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;Finished goods&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: right; background-color: #cceeff; width: 9%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;495,000&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: right; background-color: #cceeff; width: 9%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;479,000&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td valign="bottom" style="background-color: #ffffff; width: 76%; vertical-align: top;"&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: left; background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: right; background-color: #ffffff; width: 9%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: left; background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="text-align: right; background-color: #ffffff; width: 9%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; background-color: #ffffff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td valign="bottom" style="padding-bottom: 4px; background-color: #cceeff; width: 76%; vertical-align: top;"&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="padding-bottom: 4px; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="border-bottom: #000000 4px double; text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;$&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="border-bottom: #000000 4px double; text-align: right; background-color: #cceeff; width: 9%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;680,000&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; padding-bottom: 4px; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="padding-bottom: 4px; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;td valign="bottom" style="border-bottom: #000000 4px double; text-align: left; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;$&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" style="border-bottom: #000000 4px double; text-align: right; background-color: #cceeff; width: 9%; vertical-align: top;"&gt;&lt;div style="font-family: Times New Roman; color: #000000; font-size: 10pt;"&gt;719,000&lt;/div&gt;&lt;/td&gt;&lt;td nowrap="nowrap" valign="bottom" style="text-align: left; padding-bottom: 4px; background-color: #cceeff; width: 1%; vertical-align: top;"&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;/div&gt;</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>nonnum:textBlockItemType</ElementDataType><SimpleDataType>na</SimpleDataType><ElementDefenition>The entire disclosure for inventory. This may include, but is not limited to, the basis of stating inventory, the method of determining inventory cost, the major classes of inventory, and the nature of the cost elements included in inventory. If inventory is stated above cost, accrued net losses on firm purchase commitments for inventory and losses resulting from valuing inventory at the lower-of-cost-or-market may also be included. For LIFO inventory, may disclose the amount and basis for determining the excess of replacement or current cost over stated LIFO value and the effects of a LIFO quantities liquidation that impacts net income.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 210

 -SubTopic 10

 -Section 50

 -Paragraph 1

 -URI http://asc.fasb.org/extlink&amp;oid=6361739&amp;loc=d3e7789-107766



Reference 2: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 210

 -SubTopic 10

 -Section S99

 -Paragraph 1

 -Subparagraph (SX 210.5-02.6)

 -URI http://asc.fasb.org/extlink&amp;oid=6877327&amp;loc=d3e13212-122682



Reference 3: http://www.xbrl.org/2003/role/presentationRef

 -Publisher SEC

 -Name Regulation S-X (SX)

 -Number 210

 -Section 02

 -Paragraph 6

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