Note 6 - Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2019

Notes Tables

Schedule of Product Warranty Liability [Table Text Block]

Balance at December 31, 2018	$	186,000
Warranties issued during the period		43,000
Settlements made during the period		(107,000	)
Changes in liability for pre-existing warranties during the period		(39,000	)
Balance at March 31, 2019	$	83,000