Note 1 - Summary of Significant Accounting Policies (Detail) - Product warranty reserve activity is as follows: (USD $)	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Ending Balance	$ 208,745	$ 253,225
Approximation (Member)
Beginning Balance	253,000	162,000
Ending Balance	209,000	253,000
Amounts charged to expense	184,000	489,000
Actual warranty costs paid	$ (228,000)	$ (398,000)