PolarStar Airsoft Gearbox Shim set for Cylinder Conversion Kits

These precision shim sets are designed to secure an HPA cylinder firmly within the gearbox shell, preventing unwanted forward or backward movement during operation. Small variations in gearbox pin diameter between manufacturers mean cylinder conversion kits must allow enough clearance to fit the largest pins, which can sometimes result in movement when installed in gearboxes with smaller pins. If the cylinder can shift under use, nozzle alignment can change, affecting how consistently BBs are seated into the hop unit. This can lead to reduced air seal, inconsistent FPS, and overall performance loss. By correctly spacing the cylinder to match your gearbox pin size, these shims help maintain proper nozzle position and consistent air delivery. Available in multiple thicknesses to suit the most common gearbox pin diameters, these shim sets allow a more precise and secure fit across a wide range of replicas. They are fully compatible with all PolarStar cylinder conversion systems, including F2, F1, JACK, and Kythera engines. Read the full description for size compatibility.