CONDENSED CONSOLIDATED STATEMENTS OF INCOME (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (unaudited) [Abstract]
Net sales	$ 11,350	$ 14,751	$ 22,900	$ 26,994
Cost of sales	5,646	7,760	11,110	14,141
Gross profit	5,704	6,991	11,790	12,853
Operating expenses:
Engineering, design and product development	1,115	1,183	2,280	2,404
Selling and marketing	2,089	2,079	3,943	3,652
General and administrative	2,191	2,111	4,481	4,323
Operating expenses	5,395	5,373	10,704	10,379
Operating income	309	1,618	1,086	2,474
Interest and other income (expense):
Interest, net	(7)	(6)	(13)	(14)
Other, net	(142)	(97)	(52)	(87)
Interest and other income (expense)	(149)	(103)	(65)	(101)
Income before income taxes	160	1,515	1,021	2,373
Income tax provision	(26)	305	89	483
Net income	$ 186	$ 1,210	$ 932	$ 1,890
Net income per common share:
Basic (in dollars per share)	$ 0.02	$ 0.16	$ 0.12	$ 0.25
Diluted (in dollars per share)	$ 0.02	$ 0.16	$ 0.12	$ 0.24
Shares used in per-share calculation:
Basic (in shares)	7,462	7,401	7,461	7,467
Diluted (in shares)	7,597	7,660	7,607	7,782
Dividends declared and paid per common share (in dollars per share)	$ 0.09	$ 0.09	$ 0.18	$ 0.18