This is an optional Fioroni 16mm Dual Action Ergal 6 Hole Shock Piston Set, and is intended for use with the Hot Bodies D8 family of vehicles, the GS CLX and Kyosho MP9 family of vehicles, as well as any other vehicle that uses a 16mm inner diameter shock body. These dual rate shock pistons will help to reduce chassis slap, as well as improve handling and increase speed through rough track sections.
As the piston moves through the shock body, oil passes through the large holes, applying pressure to the o-rings, slowing the movement of the piston. This design gives you the option of changing the compression or rebound rate of the shock. If a faster shock re-bound is desired, face the large holes up, if faster compression is desired, face the large holes down.