Note 5 - Income Taxes - Schedule of Deferred Tax Assets (Details) - USD ($)	Mar. 31, 2023	Mar. 31, 2022
Statement [Line Items]
Accounts receivable reserves	$ 34,000	$ 34,000
Inventory	260,000	209,000
Accruals	9,000	14,000
Property and equipment and intangible assets	14,000	39,000
Net operating loss and credit carry forwards	4,437,000	4,064,000
Valuation allowance	(4,754,000)	(4,360,000)
Total deferred tax assets	$ 0	$ 0