Note 9 - Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

Schedule of Product Warranty Liability [Table Text Block]

	Year Ended December 31,
	2020			2019
Beginning balance	$	277,000		$	186,000
Warranties originated during the year		71,000			254,000
Claims settled made during the year		(212,000	)		(154,000	)
Changes in reserve estimate		18,000			(9,000	)
Ending balance	$	154,000		$	277,000