CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($)	9 Months Ended
	Feb. 28, 2018	Feb. 28, 2017
Cash flows from operating activities:
Net loss	$ (798,211)	$ (562,741)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	139,864	163,587
Stock option expense	10,927	10,009
Change in provision for allowance on accounts receivable	4,357	59,190
Inventory reserve	(465)	(12,799)
Increase in deferred rent liability	12,454	2,510
Changes in assets and liabilities:
Accounts receivable	(101,979)	(161,562)
Inventories	(224,069)	57,666
Prepaid expenses and other	(144,850)	(98,452)
Accounts payable and accrued expenses	198,044	170,869
Other assets	31,825	(9,185)
Accrued compensation	19,935	(8,472)
Net cash used in operating activities	(852,168)	(389,380)
Cash flows from investing activities:
Purchases of property and equipment	(74,303)	(95,833)
Net cash used in investing activities	(74,303)	(95,833)
Cash flows from financing activities:
Net proceeds from sales of common stock	285,733
Proceeds from exercise of stock options	18,614	138,997
Net cash provided by financing activities	304,347	138,997
Effect of exchange rate changes in cash	(6,308)	(1,001)
Net decrease in cash and cash equivalents	(628,432)	(347,217)
Cash and cash equivalents at beginning of period	1,225,462	1,888,925
Cash and cash equivalents at end of period	597,030	1,541,708
Non-cash investing and financing activities:
Subscriptions receivable	32,299
Exercise of stock options for reduction of accrued expenses		14,190
Cash paid during the period for:
Interest	37	242
Income taxes	$ 800	$ 800