Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 2,689	$ 1,041
Adjustments to reconcile net income to net cash provided by operating activities:
Allowance for doubtful accounts	17	0
Inventory reserve	180	54
Deferred tax expense	1,118	328
Depreciation and amortization	942	914
Share-based compensation expense	49	57
Realized tax benefit from stock option exercise	392	0
Changes in operating assets and liabilities:
Trade accounts receivable	657	(856)
Inventories	2,103	(4,224)
Prepaid expenses and other current assets	1,671	(1,160)
Other assets	(3)	34
Accounts payable	(312)	882
Accrued compensation and related taxes	1,057	(110)
Accrued warranty expense	112	154
Deferred revenue	48	(1)
Accrued other expenses and other current liabilities	1	(49)
Net cash provided by (used in) operating activities	10,721	(2,936)
Investing activities
Purchases of property, plant and equipment	(1,394)	(1,089)
Purchase of available-for-sale securities	(481)	(2,761)
Net cash used in investing activities	(1,875)	(3,850)
Financing activities
Dividends paid	(2,473)	0
Repurchase of common stock	(162)	0
Proceeds from issuance of common stock	30	92
Net cash provided by financing activities	(2,605)	92
(Decrease) increase in cash	6,241	(6,694)
Cash and cash equivalents, beginning of year	4,669	11,363
Cash and cash equivalents, end of year	10,910	4,669
Supplemental disclosure
Cash paid for interest	0	0
Cash paid for income taxes	50	25
Non-cash financing activity
Cashless exercise of stock options	$ 4	$ 19