INCOME TAXES - Reconciliation of Expected Provision for Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of expected provision for income taxes, computed by applying the U.S. federal income tax rate to income before taxes, to income tax expense
U.S. federal income tax rate (as a percent)	34.00%	34.00%
Expected provision for federal income taxes	$ 77,000	$ 312,000
State income taxes, net of federal benefit	7,000	15,000
Domestic manufacturers deduction	(6,000)	(33,000)
Non-deductible meals, entertainment, and life insurance	29,000	21,000
Research and development credit	(15,000)	(31,000)
Valuation allowance released on capital loss utilized		(17,000)
Other	(2,000)	3,000
Income tax expense	90,000	270,000
Deferred tax assets:
Accrued vacation	26,000	23,000
Inventories reserve	126,000	129,000
Allowance for doubtful accounts	5,000	4,000
Allowance for sales returns	37,000	13,000
Research and development credit carryforward	45,000	30,000
Accrued self-insured medical	1,000	9,000
Less valuation allowance	(45,000)	(30,000)
Total deferred tax assets	195,000	178,000
Deferred tax liabilities:
Property and equipment and other assets	(494,000)	(462,000)
Intangible assets	(86,000)	(83,000)
Net deferred tax liabilities	$ (385,000)	$ (367,000)