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, 2019
Dec. 31, 2018
Product warranties    
Beginning balance $ 46,103 $ 59,982
Warranty claims incurred (11,194) (28,000)
Provision charged to expense 4,826 14,211
Ending balance $ 39,736 $ 46,103