CONDENSED CONSOLIDATED STATEMENTS OF INCOME (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
CONSOLIDATED STATEMENTS OF OPERATIONS [Abstract]
Net sales	$ 13,596	$ 14,801	$ 27,593	$ 29,158
Cost of sales	7,166	8,818	15,070	17,290
Gross profit	6,430	5,983	12,523	11,868
Operating expenses:
Engineering, design and product development	1,020	1,089	2,013	2,325
Selling and marketing	2,034	1,859	3,706	3,652
General and administrative	2,070	1,935	4,082	3,852
Operating expenses	5,124	4,883	9,801	9,829
Operating income	1,306	1,100	2,722	2,039
Interest and other income (expense):
Interest, net	(8)	(7)	(16)	(11)
Other, net	(2)	15	(8)	16
Interest and other income (expense)	(10)	8	(24)	5
Income before income taxes	1,296	1,108	2,698	2,044
Income tax provision	429	355	888	666
Net income	$ 867	$ 753	$ 1,810	$ 1,378
Net income per common share:
Basic (in dollars per share)	$ 0.12	$ 0.10	$ 0.24	$ 0.18
Diluted (in dollars per share)	$ 0.12	$ 0.10	$ 0.24	$ 0.18
Shares used in per-share calculation:
Basic (in shares)	7,408	7,689	7,402	7,761
Diluted (in shares)	7,514	7,743	7,469	7,813
Dividends declared and paid per common share (in dollars per share)	$ 0.09	$ 0.08	$ 0.17	$ 0.16