SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Preferred Stock, Revenue Recognition, Product Warranties, Advertising, Net Income (Loss) Per Common Share (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Preferred Stock
Non-cumulative dividend rate (as a percent)	12.00%
Liquidation preference (in dollars per share)	$ 1.00
Preferred stock dividends declared (in dollars per share)	$ 0	$ 0
Revenue Recognition
Percentage of sales (as a percent)	10.00%	10.00%
Advertising
Advertising expense charged	$ 68,000	$ 131,000
Reconciliation of basic and diluted share amounts
Basic weighted average common shares outstanding	2,745,602	2,747,424
Weighted average common stock equivalents from assumed exercise of stock options (in shares)		2,121
Diluted weighted average common shares outstanding	2,745,602	2,749,545
Outstanding options excluded from computation of income per share as effect would be antidilutive (in shares)		23,250