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Inventory Components (Details) - USD ($)
Mar. 31, 2021
Dec. 31, 2020
Notes to Financial Statements    
Raw materials and sub-assemblies $ 4,087,028 $ 3,642,377
Finished goods 393,831 281,104
Inventory reserves (755,943) (727,639)
Inventories, net $ 3,724,916 $ 3,195,842