The Traxxas Rear HD Steel Splined Driveshafts with 6mm Axles are an optional upgrade intended to be used with the Traxxas Extreme Heavy Duty Suspension Upgrade kit (TRA9080). Constructed from high strength steel and using a large 6mm axle, these shafts can handle some serious abuse. The splined telescoping shafts give you full suspension articulation and a strong positive connection. Package includes two rear steel 6mm stub axles, two rear steel outer shafts, two rear steel inner shafts and mounting pins.