The RRD 2.0 shock shafts are made from 3/4-inch Nitrotec steel. The seal heads feature a combination of Buna N (standard nitrile) and Viton (fluoroelastimer) O-rings for long-lasting durability. A Buna N double-lip wiper is also utilized to wipe away would-be contaminants from the shock shaft. A polyurethane bumpstop pad is integrated into the bottom of the shock cap (arrow). The design adds cushion for harsh bottoming-out events while also acting as a pre-wiper on the shock shaft-further preserving the sealing surfaces. A high quality DU (dry) bearing is incorporated into the design of the seal head. This robust bearing helps prevent shaft deflection and, ultimately, seal failure.