Tekno RCTekno RC LLC M5 Pinion Gear 13t MOD1 5mm bore M5 Set Screw TKR4173 Gears & Differentials

By far my favorite pinion. Basically indestructible super high quality steel, huge grub screw that both holds onto the motor shaft well and is nearly impossible to strip, and laser engraved numbers so you don't have to count teeth every time haha