Condensed Consolidated Balance Sheets - USD ($)	Nov. 30, 2020	May 31, 2020
Current assets:
Cash and cash equivalents	$ 14,993,541	$ 15,159,827
Short-term investments	1,084,034	1,071,950
Accounts receivable, net	4,822,216	5,819,471
Inventory	8,867,833	10,107,437
Costs and estimated earnings in excess of billings	1,542,701	1,754,573
Other current assets	533,070	510,360
Total current assets	31,843,395	34,423,618
Maintenance and other inventory, net	1,129,350	879,050
Property and equipment, net	9,537,703	9,407,490
Other assets	198,258	195,621
Deferred income taxes	170,115	170,115
Total assets	42,878,821	45,075,894
Current liabilities:
Short-term borrowings		1,461,500
Accounts payable	878,775	1,370,175
Accrued commissions	326,430	305,885
Other current liabilities	876,483	1,663,914
Billings in excess of costs and estimated earnings	381,180	736,866
Total current liabilities	2,462,868	5,538,340
Stockholders' Equity:
Common stock and additional paid-in capital	9,942,649	9,860,006
Retained earnings	33,359,881	32,538,580
Stockholders’ equity before treasury stock	43,302,530	42,398,586
Treasury stock - at cost	(2,886,577)	(2,861,032)
Total stockholders’ equity	40,415,953	39,537,554
Total liabilities and stockholders’ equity	$ 42,878,821	$ 45,075,894