Note 9 - Product Warranty - Changes in Product Warranty Liability (Details) - USD ($)	3 Months Ended
Feb. 28, 2022	Feb. 28, 2021
Balance, beginning	$ 202,850	$ 291,453
Settlements / adjustments	21,624	33,506
Warranties issued	(109,412)	(29,378)
Balance, ending	$ 115,062	$ 295,581

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://fasb.org/us-gaap/role/ref/legacyRef
-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=123368208&loc=d3e12565-110249

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