CONDENSED CONSOLIDATED STATEMENTS OF INCOME (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CONSOLIDATED STATEMENTS OF OPERATIONS [Abstract]
Net sales	$ 12,243	$ 13,997
Cost of sales	6,381	7,904
Gross profit	5,862	6,093
Operating expenses:
Engineering, design and product development	1,221	993
Selling and marketing	1,573	1,672
General and administrative	2,212	2,012
Operating expenses	5,006	4,677
Operating income	856	1,416
Interest and other income (expense):
Interest, net	(8)	(8)
Other, net	10	(6)
Interest and other income (expense)	2	(14)
Income before income taxes	858	1,402
Income tax provision	178	459
Net income	$ 680	$ 943
Net income per common share:
Basic (in dollars per share)	$ 0.09	$ 0.13
Diluted (in dollars per share)	$ 0.09	$ 0.13
Shares used in per-share calculation:
Basic (in shares)	7,533	7,396
Diluted (in shares)	7,901	7,445
Dividends declared and paid per common share (in dollars per share)	$ 0.09	$ 0.08