5. Inventories (Tables)
 6 Months Ended
Dec. 31, 2019
Inventory Disclosure [Abstract]  
Inventories
    December 31, 2019     June 30,2019  
Raw materials   $ 1,927,500     $ 1,738,300  
Work-in-process     340,400       106,400  
Finished goods     735,900       747,600  
                 
    $ 3,003,800     $ 2,592,300