STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net sales	$ 34,834	$ 27,172
Cost of sales	21,692	17,392
Gross profit	13,142	9,780
Operating (income) expenses:
Selling expenses	577	415
General and administrative expenses	3,189	2,492
Gain on disposal of equipment	(5)	(7)
Research and development costs	2,315	1,882
Total operating expenses	6,076	4,782
Operating income	7,066	4,998
Other income (expense):
Interest and dividend income	95	268
Other income	952	45
Gain on sale of investments	25	356
Interest expense	(236)	(220)
Total other income	836	449
Income before income taxes	7,902	5,447
Income tax expense	1,790	1,299
Net income	6,112	4,148
Other comprehensive loss, net of tax:
Unrealized loss from marketable equity investments, net of income taxes	(1,037)	(396)
Comprehensive income	$ 5,075	$ 3,752
Basic & Diluted income per share:
Basic net income per share	$ 1.56	$ 0.99
Diluted net income per share	$ 1.5	$ 0.97
Weighted-average common shares outstanding:
Basic	3,910,940	4,192,365
Diluted	4,078,087	4,298,332