Accessories:M4x2.5x15 Screw pin - 2pcs4x2.5 O-ring - 4pcs(1) This is a pair of half shafts made of hardened steel with an alloy shaft cover for the Traxxas 1:8 Revo(2) This is designed with automatic adjustable length from 135mm to 150mm No self-adjusting needed.(3) The design of this steel main shaft has a wire harness to hold the screw in place therefore avoiding any screw loss and keeps the screw held tightly in place.(4) These parts are machine finished to offer a very tight snug fit, they are also light in weight to spend less power from the batteries.(5) These parts also come in many scratch resistant anodized colors.