8. PRODUCT WARRANTIES (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2015	Feb. 28, 2014
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at the beginning of the period	$ 149us-gaap_ProductWarrantyAccrual	$ 208us-gaap_ProductWarrantyAccrual	$ 223us-gaap_ProductWarrantyAccrual	$ 222us-gaap_ProductWarrantyAccrual
Accruals for warranties issued during the period	47	34	145	188
Settlement made during the period (in cash or in kind)	(34)us-gaap_ProductWarrantyAccrualPayments	(46)us-gaap_ProductWarrantyAccrualPayments	(206)us-gaap_ProductWarrantyAccrualPayments	(214)us-gaap_ProductWarrantyAccrualPayments
Balance at the end of the period	$ 162us-gaap_ProductWarrantyAccrual	$ 196us-gaap_ProductWarrantyAccrual	$ 162us-gaap_ProductWarrantyAccrual	$ 196us-gaap_ProductWarrantyAccrual

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Carrying value as of the balance sheet date of obligations incurred through that date and payable for estimated claims under standard and extended warranty protection rights granted to customers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.15(5))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph ((c)(5))

-URI http://asc.fasb.org/extlink&oid=51674963&loc=d3e12565-110249

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Represents the aggregate decrease in the liability related to payments to satisfy claims for standard and extended product warranties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph ((c)(2))

-URI http://asc.fasb.org/extlink&oid=51674963&loc=d3e12565-110249

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the aggregate increase in the liability for accruals related to standard and extended product warranties issued during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph ((c)(3))

-URI http://asc.fasb.org/extlink&oid=51674963&loc=d3e12565-110249

+ Details

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Period Type:	duration