Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Feb. 29, 2024	Feb. 28, 2023	Feb. 29, 2024	Feb. 28, 2023
Income Statement [Abstract]
Net sales	$ 1,017,000	$ 1,111,000	$ 4,299,000	$ 4,231,000
Cost of sales	(1,166,000)	(991,000)	(3,708,000)	(3,814,000)
Gross (loss) profit	(149,000)	120,000	591,000	417,000
Operating expenses:
Selling, general and administrative	1,508,000	1,379,000	4,204,000	4,589,000
Research and development	343,000	392,000	1,226,000	1,215,000
Total operating expenses	1,851,000	1,771,000	5,430,000	5,804,000
Loss from operations	(2,000,000)	(1,651,000)	(4,839,000)	(5,387,000)
Other income:
Interest and dividend income	86,000	36,000	317,000	77,000
Total other income	86,000	36,000	317,000	77,000
Loss before income taxes	(1,914,000)	(1,615,000)	(4,522,000)	(5,310,000)
Provision (benefit) for income taxes	(4,000)	(35,000)	(35,000)	(38,000)
Net loss	$ (1,918,000)	$ (1,650,000)	$ (4,557,000)	$ (5,348,000)
Basic net loss per common share	$ (0.11)	$ (0.12)	$ (0.27)	$ (0.40)
Diluted net loss per common share	$ (0.11)	$ (0.12)	$ (0.27)	$ (0.40)
Weighted average number of common and common equivalent shares:
Basic	16,821,646	13,481,490	16,821,646	13,341,000
Diluted	16,821,646	13,481,490	16,821,646	13,341,000
Net loss	$ (1,918,000)	$ (1,650,000)	$ (4,557,000)	$ (5,348,000)
Other comprehensive income (loss), net of tax:
Foreign currency translation	2,000	(15,000)	8,000	(37,000)
Comprehensive loss	$ (1,916,000)	$ (1,665,000)	$ (4,549,000)	$ (5,385,000)