12mm Size Hex,please make sure you use the 12mm Hex. Does NOT fit for stock 14mm hex wheels.Only fit for modified rc car which has12mm hex hubs wheels tires. The 12mm hex wheel hubs compatible with 1/10 Arrma Senton Granite Typhon Vorteks 3S Big Rock rc car. The RC 12mm drive hub are made of aluminum alloy,durable in use. Come with pins & screws.Easy to install and upgrade from the original part. A great replacement part for your rc car. Item Name:12mm Wheel Hex Hub Hex Diameter:12mm; Thickness: 7mm; Diameter of Hole: 5mm; Color: Red/Black/Blue/Silver(Optional) Weight:10g/Set Package List: 4Pcs/Set 12mm Wheel Hex Drive Hub