Geographic Information (Details) - Financial information about foreign and domestic operations and export sales - USD ($)	3 Months Ended		6 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2019	Nov. 30, 2018
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	$ 1,596,408	$ 1,500,791	$ 2,790,823	$ 2,773,661
UNITED STATES
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	109,000	140,000	224,000	282,000
Asia [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	797,000	672,000	1,460,000	1,320,000
Europe [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	416,000	522,000	717,000	914,000
South America [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	24,000	56,000	71,000	127,000
Middle East [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	241,000	111,000	309,000	131,000
Other [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	$ 10,000		$ 10,000