STOCK PLANS AND STOCK-BASED COMPENSATION - Stock option activity (Details) - $ / shares	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Number of Shares
Balance, beginning of year	23,332	43,332
Options exercised	(6,000)	(5,000)
Balance, end of year	17,332	38,332
Weighted Average Exercise Price
Balance, beginning of year	$ 2.78	$ 2.69
Options exercised	2.78	1.97
Balance, end of year	$ 2.78	$ 2.78