Note 8 - Product Warranty - Changes In Product Warranty Liability (Details) - USD ($)	3 Months Ended
Feb. 28, 2018	Feb. 28, 2017
Balance, beginning	$ 68,451	$ 134,373
Settlements / adjustments	(82,673)	(72,949)
Warranties issued	68,357	64,248
Balance, ending	$ 54,135	$ 125,672

Amount as of the balance sheet date of the aggregate standard product warranty liability. Does not include the balance for the extended product warranty liability.

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)(1),(c)(5)
-URI http://asc.fasb.org/extlink&oid=68068213&loc=d3e12565-110249

Name:	us-gaap_StandardProductWarrantyAccrual
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant