This is Set of Hot Racing Piggybacks for the Stock or Hot Racing 1/16 Shocks.
These items replace the shock cap on the original Or Hot Racing Shocks.

Green and Black anodized
The piggyback design is built to reduce air bubbles and provide
additional shock oil volume.
CNC Aluminum construction
HR logo on the piggyback (reservoir)

Two piggyback assemblies
Two Spring retainers

Installation, refilling the shocks and bleeding them