CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (115)	$ (2,170)	$ (4,978)
Adjustments to reconcile net loss to net cash provided by operating activities:
Allowance for sales returns, doubtful accounts and other	4	(3)	(8)
Provision for excess and obsolete inventories	588	1,172	1,067
Depreciation and amortization	1,532	1,459	1,633
Stock-based compensation	1,877	1,850	2,077
Amortization of premium on investments	74	209	593
Changes in assets and liabilities, net of acquisition:
Accounts receivable	1,125	782	(11)
Inventory	(2,625)	66	(1,294)
Prepaid expenses and other assets	103	102	2,854
Accounts payable	(887)	(441)	(1,915)
Accrued expenses and other liabilities	911	(2,081)	811
Deferred revenue	(534)	(485)	292
Net cash provided by operating activities	2,053	460	1,121
Cash flows from investing activities:
Purchase of investments	(18,563)	(14,149)	(16,009)
Sales and maturities of short-term investments	23,600	23,585	39,699
Acquisition		(4,359)
Restricted cash		(2,984)
Purchases of property and equipment	(219)	(1,158)	(481)
Net cash provided by investing activities	4,818	935	23,209
Cash flows from financing activities:
Repurchase of common stock	(7,112)	(7,026)	(30,026)
Proceeds from issuance of common stock under employee stock plans	2,014	818	952
Net cash used in financing activities	(5,098)	(6,208)	(29,074)
Net increase (decrease) in cash and cash equivalents	1,773	(4,813)	(4,744)
Cash and cash equivalents at beginning of the period	31,963	36,776	41,520
Cash and cash equivalents at end of the period	33,736	31,963	36,776
Non-cash financing activities:
Purchases of property and equipment through accounts payable and accruals			6
Supplemental cash flow information:
Net cash paid (received) for income taxes	$ 1,339	$ 78	$ (2,394)