XML 49 R30.htm IDEA: XBRL DOCUMENT v3.6.0.2
Schedule of Valuation and Qualifying Accounts (Details) - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Allowance for Doubtful Accounts    
Balance at beginning of year $ 150,000 $ 150,000
Charges to statement of income 1,566 3,824
Write-offs (1,566) (3,824)
Balance at end of year 150,000 150,000
Inventory Valuation Reserve    
Balance at beginning of year 577,000 618,000
Charges to statement of income 80,793 77,577
Write-offs (95,793) (118,577)
Balance at end of year $ 562,000 $ 577,000