<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><Version>2.2.0.25</Version><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><ReportLongName>1040 - Disclosure - Inventories</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelColumn>false</LabelColumn><CurrencyCode>USD</CurrencyCode><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName>1/1/2011 - 3/31/2011
USD ($)

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margin-bottom:0pt'&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;font-weight:bold;margin-left:0px;"&gt;4. &lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;font-weight:bold;"&gt;   &lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;font-weight:bold;"&gt;Inventories&lt;/font&gt;&lt;/p&gt;&lt;p style='margin-top:6pt; margin-bottom:0pt'&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;margin-left:17px;"&gt;As of &lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;"&gt;March 31&lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;"&gt;, &lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;"&gt;2011&lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;"&gt; and December&amp;#160;31, &lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;"&gt;2010&lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;"&gt;, inventories consisted of the following:&lt;/font&gt;&lt;/p&gt;&lt;p style='margin-top: 0pt; margin-bottom: 0pt;'&gt;&lt;/p&gt;&lt;div&gt;&lt;table style="border-collapse:collapse;margin-top:20px;"&gt;&lt;tr style="height: 44px"&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 380px; text-align:left;border-color:#000000;min-width:380px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 9px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 94px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-WEIGHT: bold;FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;TEXT-ALIGN: center;"&gt;March 31,
2011&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 9px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 94px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-WEIGHT: bold;FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;TEXT-ALIGN: center;"&gt;December 31, 2010&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr style="height: 20px"&gt;&lt;td colspan="2"  style="width: 389px; text-align:left;border-color:#000000;min-width:389px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;Raw materials and purchased components&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:9px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;$&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 94px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;157,442&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 9px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:9px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;$&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 94px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;158,163&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr style="height: 20px"&gt;&lt;td colspan="2"  style="width: 389px; text-align:left;border-color:#000000;min-width:389px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;Work in process&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 94px; text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;53,388&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 94px; text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;56,345&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr style="height: 20px"&gt;&lt;td colspan="2"  style="width: 389px; text-align:left;border-color:#000000;min-width:389px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;Finished goods&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 94px; text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;590,580&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 94px; text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;475,641&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr style="height: 20px"&gt;&lt;td colspan="2"  style="width: 389px; text-align:left;border-color:#000000;min-width:389px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;Health care supplies&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 94px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;110,947&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 9px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 94px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;118,948&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr style="height: 21px"&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 380px; text-align:left;border-color:#000000;min-width:380px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;Inventories&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:9px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;$&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 94px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;912,357&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 9px; text-align:left;border-color:#000000;min-width:9px;"&gt;&amp;#160;&lt;/td&gt;&lt;td   style="width: 9px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:9px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;$&lt;/font&gt;&lt;/td&gt;&lt;td   style="width: 94px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:94px;"&gt;&lt;font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 10pt;COLOR: #000000;"&gt;809,097&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;/div&gt;&lt;p style='margin-top: 0pt; margin-bottom: 0pt;'&gt;&lt;/p&gt;&lt;p style='margin-top:12pt; margin-bottom:0pt'&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;margin-left:17px;"&gt;The Company has a contingent liability of up to $&lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;"&gt;65,041&lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;"&gt;, subject to renegotiation of certain supply contracts.&lt;/font&gt;&lt;/p&gt;</NonNumbericText><NonNumericTextHeader>4.    InventoriesAs of March 31, 2011 and December&amp;#160;31, 2010, inventories consisted of the following:&amp;#160;&amp;#160;&amp;#160;March 31,
2011&amp;#160;&amp;#160;December</NonNumericTextHeader><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell></Cells><OriginalInstanceReportColumns /><Unit>Other</Unit><ElementDataType>us-types:textBlockItemType</ElementDataType><SimpleDataType>string</SimpleDataType><ElementDefenition>This element represents the complete disclosure related to 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 AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 43
 -Chapter 3
 -Section A
 -Paragraph 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 02
 -Paragraph 6
 -Subparagraph a, b, c
 -Article 5

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