The Best O-Rings For Silencing Your Keyboard - Switch and Click
40 O-Rings (10 Pack) - Danco
Red Color Silicone 40A O Ring - China O-Ring, Auto Parts | Made-in-China.com
Amazon.com: 200pcs Rubber O-Ring Keyboard Switch Dampeners Make Your Mechanical Keyboard Quieter with Keycap Remover Suitable for Cherry MX Key Kit Dampers 40A-L-0.2mm Reduction (Transparent) : Electronics
Glorious sell 40A/70A O-Rings at both 1.5 and 2.5mm for $10. Thought I'd mention this as usually people only talk about WASD. (link in comments) : r/MechanicalKeyboards
Wholesale Mechanical Keyboard Keycap 40A Silicone Rubber O Ring for Cherry Mx - China Wholesale Mechanical Rubber O Ring, Keyboard Keycap Rubber O Ring | Made-in-China.com
DANCO #40 O-Ring (10-Pack) 96754 - The Home Depot
ENHANCE Mechanical Keyboard O Ring Ultra-Quiet Switch Dampeners 40A Clear (140pcs) , Key Cap Remover , Cleaning Brush , Cloth and Accessory Bag - Mod Kit for Cherry MX , TTC ,