Condensed Consolidated Balance Sheets - USD ($)	Nov. 30, 2018	May 31, 2018
Current assets:
Cash and cash equivalents	$ 4,964,376	$ 2,858,323
Short-term investments	1,047,971	1,039,082
Accounts receivable, net	4,993,920	6,265,864
Inventory	12,081,725	11,317,775
Costs and estimated earnings in excess of billings	5,953,406	6,356,963
Other current assets	481,880	447,162
Total current assets	29,523,278	28,285,169
Maintenance and other inventory, net	870,341	885,651
Property and equipment, net	9,705,412	9,935,625
Other assets	188,388	185,730
Deferred income taxes	219,115	219,115
Total assets	40,506,534	39,511,290
Current liabilities:
Accounts payable	2,119,545	1,460,175
Accrued commissions	969,648	983,260
Billings in excess of costs and estimated earnings	793,578	2,043,002
Other current liabilities	1,818,422	1,412,502
Total current liabilities	5,701,193	5,898,939
Stockholders' Equity:
Common stock and additional paid-in capital	9,554,272	9,482,630
Retained earnings	28,080,428	26,959,080
Stockholders’ equity before treasury stock	37,634,700	36,441,710
Treasury stock -  at cost	(2,829,359)	(2,829,359)
Total stockholders’ equity	34,805,341	33,612,351
Total liabilities and stockholders’ equity	$ 40,506,534	$ 39,511,290