Traxxas replacement GTR shock caps and spring retainers for the Revo. Replacement GTR shock retainers for the Traxxas Nitro Revo Monster Truck. INCLUDES: Two Black Nylon GTR Shock Caps. Two Black Nylon GTR Spring Adjusters. Two Black Nylon GTR Spring Retainers. Two Black Nylon GTR Shock Bottoms. Four Silver Metal Hollow Balls