About skid patches.... (pulled from surplace.fr/ffgc - fixed gear calculator) : r/FixedGearBicycle
Microstrip Patch Antenna Calculator for RF Designers
Amazon.com: "5318008 Calculator" - Calculator PVC Morale Patch - Funny Morale, Tactical, Military Patch - Velcro Patches, Military Patches - Perfect for Your Tactical Military Army Gear, Backpack, Cap, Vest : Sports & Outdoors