Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income	$ 1,041	$ 1,623
Adjustments to reconcile net income to net cash provided by operating activities:
Allowance for doubtful accounts	0	(35)
Inventory reserve	(18)	9
Deferred tax expense	328	875
Depreciation and amortization	914	1,185
Share-based compensation expense	57	46
Changes in operating assets and liabilities:
Accounts receivable	(856)	(387)
Inventories	(4,152)	(546)
Prepaid expenses and other current assets	(1,160)	(1)
Other assets	34	52
Accounts payable	882	453
Accrued compensation and related taxes	(110)	467
Accrued warranty expense	154	92
Deferred revenue	(1)	75
Accrued other expenses and other current liabilities	(49)	63
Net cash provided by operating activities	(2,936)	3,971
Investing activities
Purchases of property, plant and equipment	(1,089)	(697)
Purchase of available-for-sale securities	(2,761)	0
Net cash used in investing activities	(3,850)	(697)
Financing activities
Proceeds from issuance of common stock	92	144
Net cash provided by financing activities	92	144
(Decrease) increase in cash	(6,694)	3,418
Cash and cash equivalents, beginning of year	11,363	7,945
Cash and cash equivalents, end of year	4,669	11,363
Supplemental disclosure
Cash paid for interest	0	0
Cash paid for income taxes	25	0
Non-cash financing activity
Cashless exercise of stock options	$ 19	$ 2