CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONDENSED CONSOLIDATED STATEMENTS OF INCOME [Abstract]
Net sales	$ 45,748	$ 54,587	$ 56,311
Cost of sales	23,813	27,844	29,649
Gross profit	21,935	26,743	26,662
Operating expenses:
Engineering, design and product development	4,393	4,576	4,303
Selling and marketing	8,033	7,203	7,561
General and administrative	9,166	8,205	7,984
Operating expenses	21,592	19,984	19,848
Operating income	343	6,759	6,814
Interest and other income (expense):
Interest expense	(28)	(27)	(33)
Interest income	17	0	0
Other, net	35	(266)	(9)
Interest and other income (expense)	24	(293)	(42)
Income before income taxes	367	6,466	6,772
Income tax (benefit) provision	(149)	1,040	3,561
Net income	$ 516	$ 5,426	$ 3,211
Net income per common share:
Basic (in dollars per share)	$ 0.07	$ 0.73	$ 0.43
Diluted (in dollars per share)	$ 0.07	$ 0.70	$ 0.42
Shares used in per-share calculation:
Basic (in shares)	7,466	7,444	7,423
Diluted (in shares)	7,677	7,759	7,592
Dividends declared and paid per common share (in dollars per share)	$ 0.36	$ 0.36	$ 0.35