MX Rubber O-Rings Switch Dampeners DBlack Clear Red Blue Cherry MX Keyboard Dampers Keycap O Ring - AliExpress
Keyboard O-Rings dampers key cap switch mechanical / Cherry MX Rubber orings Red 40A - AliExpress
Amazon.com: Griarrac Kailh Box Switch Tester Mechanical Keyboards Retooled Sampler 9-Key Switch Testing Tool, with Keycap Puller and 18 O Rings, Navy Jade White Red Black Brown Yellow Blue Orange Switches :
Cherry MX Red vs Brown Switches, Red vs Blue O-Rings Review | Taugrim's MMO Blog