Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net loss	$ (5,119)	$ (4,194)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	200	294
Stock-based compensation	523	430
Provision for doubtful accounts receivable	38	(11)
Provision for slow-moving and obsolete inventories and valuation reserves	(303)	(409)
Provision for warranties	106	15
Amortization of loan origination fees	(45)	0
Loss (gain) on dispositions of property and equipment	15	(15)
Changes in operating assets and liabilities:
Accounts receivable	358	237
Inventories	693	388
Prepaid and other assets	447	(435)
Accounts payable	(1,526)	1,471
Accrued and other liabilities	(580)	(79)
Deferred revenue	(17)	8
Total adjustments	(1)	1,894
Net cash used in operating activities	(5,120)	(2,300)
Cash flows from investing activities:
Acquisitions of property and equipment	(28)	(57)
Proceeds from the sale of property and equipment	0	240
Net cash (used in) provided by investing activities	(28)	183
Cash flows from financing activities:
Proceeds from exercises of stock options and employee stock purchase plan purchases	0	21
Common stock withheld to satisfy income tax withholding on vesting of restricted stock units	(116)	(39)
Principal payments under finance lease obligations	(1)	0
Proceeds from convertible notes	1,700	0
Net repayments on credit line borrowings	(568)	0
Net cash provided by (used in) financing activities	1,015	(18)
Effect of exchange rate changes on cash	5	(7)
Net decrease in cash and cash equivalents	(4,128)	(2,142)
Cash and cash equivalents, beginning of period	6,335	10,761
Cash and cash equivalents, end of period	2,207	8,619
Classification of cash and cash equivalents:
Cash and cash equivalents, end of period	$ 6,335	$ 10,761