Note 12 - Income Taxes (Detail) - Deferred tax assets and liabilities: (USD $)	Mar. 31, 2013	Mar. 31, 2012
Stock option compensation	$ 360,000	$ 353,000
Inventory reserves	296,000	290,000
Deferred tax assets	1,002,000	1,069,000
Prepaid expenses	(232,000)	(286,000)
Property and equipment	(429,000)	(417,000)
Gross deferred tax liabilities	(661,000)	(703,000)
Net deferred tax asset	341,000	366,000
Other	16,000	21,000
Warranty reserve	78,000	95,000
Accrued Vacation [Member]
Deferred tax assets	227,000	202,000
Accounts Receivable Reserve [Member]
Deferred tax assets	$ 25,000	$ 108,000