3. REVENUE (Details 1) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2021	Feb. 29, 2020
Net sales	$ 5,267	$ 6,111	$ 8,962	$ 18,518
United States
Net sales	1,113	5,014	3,124	12,698
Asia
Net sales	4,122	891	5,723	4,758
Europe
Net sales	$ 32	$ 206	$ 115	$ 1,062

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details