Significant Accounting Policies (Tables)

6 Months Ended

Nov. 30, 2019

Accounting Policies [Abstract]

Schedule of Inventory, Current [Table Text Block]

	November 30, 2019		May 31, 2019
Raw materials	$	1,209,000	$	1,208,000
Work in progress		835,000		771,000
Finished products		147,000		172,000
Total	$	2,191,000	$	2,151,000

Share-based Payment Arrangement, Option, Activity [Table Text Block]

		Exercise Price Weighted Average
	Option Shares
Outstanding May 31, 2019	1,476,209	$	2.07
Granted	--		--
Forfeited	(35,250)		3.26
Exercised	(54,125)		0.92
Outstanding November 30, 2019	1,386,834	$	2.09

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Six Months Ended November 30,				Three Months Ended    November 30,
	2019		2018		2019		2018
Numerator:
Loss from continuing operations	$	(991,556)	$	(928,984)	$	(485,260)	$	(477,244)
Denominator for basic net loss    Per common share		9,780,713		8,995,575		9,817,363		9,061,617
Effect of dilutive securities:
Options		--		--		--		--
Denominator for diluted net loss   per common share		9,780,713		8,995,575		9,817,363		9,061,617
Basic net loss per common share	$	(0.10)	$	(0.10)	$	(0.05)	$	(0.05)
Diluted net loss per common share	$	(0.10)	$	(0.10)	$	(0.05)	$	(0.05)