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PATENTS (Details) - USD ($)
Mar. 31, 2021
Dec. 31, 2020
Patents, net $ 1,512,000 $ 1,578,000
Patents [Member]    
Gross carrying amount 7,856,000 7,848,000
Accumulated amortization (6,344,000) (6,270,000)
Patents, net $ 1,512,000 $ 1,578,000