Axle Nut for 12mm Axle This axle nut is for 12mm axles and works with an 18mm wrench. Compatibility: (Electric scooter manufacturers sometimes change parts mid-production so verify this part is the correct type and size before ordering.) Gotrax Apex, Apex LE, Apex Pro, G3, G4, GMAX, GMAX ULTRA, Gxl V2, Rival, Xr Ultra, Xr Elite