Note 12 - Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Inventory obsolescence reserve	$ 53,000	$ 62,000
Product refund reserve		7,000
Deferred revenue	91,000
Organization costs	117,000	127,000
Deferred compensation	97,000	94,000
Depreciation and amortization, deferred tax assets	2,000
Miscellaneous accrued expenses	23,000	13,000
Domestic net operating loss carryforwards	451,000	186,000
Foreign net operating loss carryforwards	3,118,000	3,413,000
Valuation allowance	(3,845,000)	(3,767,000)
	107,000	135,000
Deferred tax liabilities:
Depreciation and amortization, deferred tax liabilities		28,000
Foreign currency exchange	107,000	107,000
	107,000	135,000
Net deferred tax assets (liabilities)