4. BALANCE SHEET DETAIL - Intangible assets (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Mar. 31, 2022
Gross Carrying Amount	$ 4,890,000		$ 4,890,000		$ 4,890,000
Accumulated Amortization	(2,984,000)		(2,984,000)		(2,867,000)
Total	1,906,000		1,906,000		2,023,000
Amortization of intangible assets	58,000	$ 58,000	117,000	$ 117,000
Product Designs
Gross Carrying Amount	590,000		590,000		590,000
Accumulated Amortization	(590,000)		(590,000)		(590,000)
Patents
Gross Carrying Amount	4,220,000		4,220,000		4,220,000
Accumulated Amortization	(2,314,000)		(2,314,000)		(2,197,000)
Total	1,906,000		1,906,000		2,023,000
Software.
Gross Carrying Amount	80,000		80,000		80,000
Accumulated Amortization	$ (80,000)		$ (80,000)		$ (80,000)