Replace 5358 front Will fit Traxxas 5358 E-Revo 2.0 vxl Revo Summit Slayer Pro4x4 Aluminum more durable and cool Progressive-rate 2 rocker arms determine how much the compressive force at the wheel will vary with suspension travel. The higher the rate, the more the suspension will stiffen as the wheel moves upward. Rocker arms are available in 3 progressive rates with 1 having softest rate and 3 being the stiffest. Progressive rate 2 will sharpen handling and reduce brake dive compared to progressive rate 1. 2pcs Aluminum Front Rocker Arm Progressive-2 (90-T) Blue for Traxxas Revo E-Revo 2.0 vxl Summit Slayer Pro4X4 5358