Quarterly report pursuant to Section 13 or 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 ($)
3 Months Ended 12 Months Ended
Mar. 31, 2020
Dec. 31, 2019
Product warranties    
Beginning balance $ 58,791 $ 46,103
Warranty claims incurred (2,947) (66,803)
Provision charged to expense 5,898 79,491
Ending balance $ 61,742 $ 58,791