Features: durability, reliability, stability, safety, environmental protection. Compatible with Stihl FS55 FS45 BR45 KM55 HL45 HS45 HS55 Trimmer. Metal Package Content: 1 * Cylinder 1 * Piston 2 * Ring 1 * Pin 2 * Clips Only the above package content, other products are not included. The allowable measurement error is +/- 1-3cm.