Geographic Information (Details) - Financial information about foreign and domestic operations and export sales - USD ($)	3 Months Ended		6 Months Ended
	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014
Revenues from sales to unaffiliated customers:
Net sales	$ 1,165,080	$ 1,133,600	$ 2,452,073	$ 2,168,050
UNITED STATES
Revenues from sales to unaffiliated customers:
Net sales	218,000	220,000	405,000	473,000
Asia [Member]
Revenues from sales to unaffiliated customers:
Net sales	419,000	102,000	852,000	118,000
Europe [Member]
Revenues from sales to unaffiliated customers:
Net sales	473,000	693,000	1,092,000	1,444,000
South America [Member]
Revenues from sales to unaffiliated customers:
Net sales	32,000	3,000	49,000	6,000
Middle East [Member]
Revenues from sales to unaffiliated customers:
Net sales	$ 23,000	111,000	$ 54,000	113,000
Other Foreign [Member]
Revenues from sales to unaffiliated customers:
Net sales		$ 5,000		$ 14,000