Inventories (Changes In Inventory Obsolescence Reserve) (Details) - USD ($)	12 Months Ended
Apr. 30, 2020	Apr. 30, 2019
Inventories [Abstract]
Beginning balance	$ 1,343,972	$ 1,202,932
Provision for obsolescence	221,499	268,234
Write-offs	(215,109)	(127,194)
Ending balance	$ 1,350,362	$ 1,343,972

Amount of valuation reserve for inventory.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 35
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Name:	us-gaap_InventoryValuationReserves
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant