Note 9 - Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

2019	$	311,000
2020		301,000
2021		310,000
2022		319,000
2023		329,000
Thereafter		139,000
Total	$	1,709,000

Schedule of Product Warranty Liability [Table Text Block]

	Year Ended December 31,			Six Months Ended December 31,			Year Ended June 30,
	2018			2017			2017
Beginning balance	$	291,000		$	588,000		$	566,000
Warranties issued during the period		199,000			95,000			120,000
Settlements made during the period		(252,000	)		(359,000	)		(93,000	)
Changes in liability for pre-existing warranties during the period		(52,000	)		(33,000	)		(5,000	)
Ending balance	$	186,000		$	291,000		$	588,000