Quarterly report pursuant to Section 13 or 15(d)

Contract Assets and Contract Liabilities (Details 1)

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Contract Assets and Contract Liabilities (Details 1) - USD ($)
Mar. 31, 2021
Dec. 31, 2020
Costs and estimated earnings amounts on uncompleted contracts included in balance sheets    
Contract assets $ 1,902,577 $ 1,303,136
Contract liabilities (1,133,328) (1,774,740)
Net contract assets (liabilities) $ 769,249 $ (471,604)