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Significant Accounting Policies (Details) - Inventories - USD ($)
Aug. 31, 2018
May 31, 2018
Inventories [Abstract]    
Raw materials $ 989,000 $ 1,000,000
Work in progress 923,000 854,000
Finished products 296,000 325,000
Total $ 2,208,457 $ 2,178,777