Empi 20-7076 Vw Piston Barrel Shims. Barrel Shim Spacers Sit In Between The Engine Case And The Bottom Of The Piston Barrel. Commonly Used For Setting Up Piston Deck Height For Desired Compression Ratio's On Volkswagen Air Cooled Engines. Specs: 90.5mm And 92mm Piston Bore Size .090 Thickness Applications: Volkswagen Type 1 Bug/Beetle Volkswagen Type 1 Karmann Ghia Volkswagen Type 2 Bus Volkswagen Type 3 Squareback, Fastback, Notchback Set Of 4