CONDENSED CONSOLIDATED STATEMENTS OF INCOME (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
CONSOLIDATED STATEMENTS OF OPERATIONS [Abstract]
Net sales	$ 15,524	$ 14,474	$ 43,117	$ 43,632
Cost of sales	8,005	8,559	23,075	25,849
Gross profit	7,519	5,915	20,042	17,783
Operating expenses:
Engineering, design and product development	1,147	1,133	3,160	3,458
Selling and marketing	1,895	1,808	5,601	5,460
General and administrative	1,886	1,737	5,968	5,589
Operating expenses	4,928	4,678	14,729	14,507
Operating income	2,591	1,237	5,313	3,276
Interest and other income (expense):
Interest, net	(9)	(7)	(25)	(18)
Other, net	0	(3)	(8)	13
Interest and other income (expense)	(9)	(10)	(33)	(5)
Income before income taxes	2,582	1,227	5,280	3,271
Income tax provision	769	344	1,657	1,010
Net income	$ 1,813	$ 883	$ 3,623	$ 2,261
Net income per common share:
Basic (in dollars per share)	$ 0.24	$ 0.12	$ 0.49	$ 0.29
Diluted (in dollars per share)	$ 0.24	$ 0.12	$ 0.48	$ 0.29
Shares used in per-share calculation:
Basic (in shares)	7,408	7,498	7,404	7,673
Diluted (in shares)	7,586	7,549	7,504	7,724
Dividends declared and paid per common share (in dollars per share)	$ 0.09	$ 0.08	$ 0.26	$ 0.24