Note: Installation guide not included; professional installation is strongly recommended. Please verify compatibility to ensure the item meets your needs. Clutch Drum Chain Sprocket for Chainsaw. Part numbers: 503873072, 578097901, 503873073, 503873071, 503255201, 108565X, GB HU414A7N. Warning: Confirm your model before purchase. Compatible with: 340, 340E, 345, 345E, 350, 351, 353, 445, 445 II, 445E, 445E II, 450, 450E, 450E II chainsaw models. Product appearance or color may vary slightly between batches due to updates; these variations do not affect functionality. Color: As shown. Material: Metal. Package includes: 1 x Clutch, 1 x Clutch Drum Chain Sprocket, 1 x Needle Bearing. No additional items included. Note: Lighting and display settings may cause slight color differences between the image and the actual item. Measurement error allowance: +/- 1-3 cm.