Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities
Net (loss) income	$ (1,565)	$ 503
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Inventories allowances	49	(31)
Deferred tax benefit	(164)	178
Depreciation and amortization	575	439
Share-based compensation expense	68	38
Restricted stock unit compensation expense	74	73
(Gain) loss on investment in securities	(444)	1,201
Changes in operating assets and liabilities:
Trade accounts receivable	628	(1,459)
Inventories	(1,840)	1,608
Prepaid expenses and other current assets	269	(99)
Other assets	(4)	23
Accounts payable	1,246	(2,437)
Accrued compensation and related taxes	(691)	251
Accrued warranty expense	(106)	26
Deferred revenue	417	582
Accrued other expenses and other current liabilities	155	(185)
Net cash (used in) provided by operating activities	(1,333)	711
Investing activities
Purchases of property, plant and equipment	(1,462)	(569)
Investment in securities	0	(3,741)
Proceeds from sale of available-for-sale securities	0	8,335
Net cash (used in) provided by investing activities	(1,462)	4,025
Financing activities
Proceeds from issuance of common stock	2	0
Cash dividends declared and paid	(510)	(544)
Repurchase of common stock	(550)	(616)
Net cash used in financing activities	(1,058)	(1,160)
Net change in cash and cash equivalents	(3,853)	3,576
Cash and cash equivalents, beginning of period	11,268	7,147
Cash and cash equivalents, end of period	7,415	10,723
Supplemental disclosure
Cash paid for interest	0	0
Income tax paid	0	0
Non-cash financing activity
Restricted stock units issued	$ 140	$ 140