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Inventory (Details) - USD ($) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Dec. 31, 2018
Inventory Disclosure [Abstract] |  |  |
Allowance for inventory obsolescence | $ 19,000 |  | $ 19,000
Raw materials - current | 29,821,000 |  | 26,152,000
Raw materials - long term, net | 3,997,000 |  | 3,980,000
Finished Goods | 1,022,000 |  | 1,022,000
Work in process | 4,656,000 |  | 3,800,000
Inventory, net | 39,496,000 |  | $ 34,954,000
Write-offs of obsolete inventory against allowance | $ 0 | $ 0 |

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