Annual report pursuant to Section 13 and 15(d)

A. BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Details-Product warranties)

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A. BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Details-Product warranties) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Product warranties    
Beginning balance $ 58,791 $ 46,103
Warranty claims incurred (20,499) (66,803)
Provision charged to expense 7,036 79,491
Ending balance $ 45,328 $ 58,791