12 mm blue-anodized aluminum hex adapters feature a 6 mm inner diameter to accept the beefier axles found in 6451 and 6452 steel CV driveshafts. The 12 mm hex adapters are compatible with Traxxas short course and rally wheels and most standard 12 mm hex-style wheels. The kit includes a drill bit to widen the wheels to accept a 6 mm axle. Hex adapters require the following items for installation on Slash 4X4, Rally, and Stampede 4X4: 6451 (x2), 6452 (x2), 6439, 6455, 5117 (x3).