TRIUMPH BSA AMAL 376 626 CARB AIR FILTER ADAPTER RING PN# 70-4576 E4576 71-2086 | eBay
Air Filter Inlet Adapter/ Velocity Stack
R-ep Reduce Adapter For 76mm 3inch Cone Air Filter 77mm To 70mm 65mm 60mm Universal Rubber Reducing Ring 3inch To 2.75inch 2.5'' - Air Intakes Parts - AliExpress
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Small Diameter Air Cleaner Adapter Ring, 2-5/16 Inch to 2-5/8 Inch