Note 11 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Operating lease liabilities	$ 1,601	$ 1,123
Inventories	321	247
Accrued vacation pay and stock-based compensation	252	279
Net operating loss (state and foreign)	241	280
Allowance for doubtful accounts	44	44
Accrued warranty	13	19
Acquisition costs	10	12
Tax credit carryforwards	5	112
Other	71	13
Total	2,558	2,129
Valuation allowance	(169)	(234)
Deferred tax assets	2,389	1,895
Deferred tax liabilities:
Net intangible assets	(2,697)	(2,923)
Right of use assets	(1,400)	(1,066)
Depreciation of property and equipment	(214)	(169)
Deferred tax liabilities	(4,311)	(4,158)
Net deferred tax liabilities	$ (1,922)	$ (2,263)