HPI piston pin and retainer are constructed of silver metal. This mounts inside the piston and holds the con rod onto the piston. This is also referred to as the Wrist Pin.
Length of Piston Pin: .61" (15mm)
Diamter of Piston Pin: .15" (3.8mm)
Diamter of Retainer: .14" (3.5mm)
Assembly onto Engine.