High quality aluminum. The precise, calibrated interior diameter is 2.38 mm (3/32), standard for Pioneer, SCX, Scalextric, Sloter, Slot It and most other brands. For use with these tires: HSR 17.5 x...
Lightweight aluminum crown gear. The number of teeth is molded on the backside of each gear. As a guide: less crown gear teeth = more speed, & more crown gear teeth = better acceleration. Fits 2...