Griarrac Cherry MX Switch Tester 12-Key Mechanical Keyboard Sampler Switch Testing Tool with Keycap Puller and 24 O Rings, 40A-L & 40A-R (Printed PBT Keycap Include Linear Gray) - Walmart.com
Cherry Mx Rubber O-rings 120pcs Switch Dampeners Dark Black Clear Red Blue Cherry Mx Keyboard Dampers Keycap O Ring Replace Part - Keyboards - AliExpress
Cherry MX Red vs Brown Switches, Red vs Blue O-Rings Review | Taugrim's MMO Blog