CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CONSOLIDATED STATEMENTS OF INCOME [Abstract]
Net sales	$ 8,301	$ 10,247
Cost of sales	5,112	5,329
Gross profit	3,189	4,918
Operating expenses:
Engineering, design and product development	1,803	1,385
Selling and marketing	1,443	2,208
General and administrative	2,609	2,620
Operating expenses	5,855	6,213
Operating loss	(2,666)	(1,295)
Interest and other (expense) income:
Interest, net	(13)	3
Other, net	(83)	(165)
Interest and other expense	(96)	(162)
Loss before income taxes	(2,762)	(1,457)
Income tax benefit	(556)	(465)
Net loss	$ (2,206)	$ (992)
Net loss per common share:
Basic (in dollars per share)	$ (0.25)	$ (0.13)
Diluted (in dollars per share)	$ (0.25)	$ (0.13)
Shares used in per-share calculation:
Basic (in shares)	8,948	7,507
Diluted (in shares)	8,948	7,507