Traxxas replacement gears and shafts for the EZ-Start System. Steel main gear. Nylon and nylon/metal gears. Metal gear shafts.INCLUDED: One 29T Steel Main Gear One 18T x 10T Nylon/Metal Gear One 37T x 11T Nylon Gear Two 3 x 14mm Metal Shafts One 3 x 5mm Brass Bushing. NOTES: Most GP models made by Traxxas have the EZ-Start system