General description AlwaysH 3/8' Clutch Sprocket Kit is designed for Stihl chainsaw models including 017, 018, MS170, MS180, 021, 023, 025, MS210, MS230, and MS250. This high-quality sprocket kit helps you easily repair your chainsaw, restoring it to peak performance and making it run like new. Technical specifications 3/8 LP Pitch Spur Sprocket OEM Part Numbers: # 1123 640 2003, 1123 640 2073 Clutch assembly replaces: # 1123 160 2001 Worm gear replaces: # 1123 640 7102 Compatibility and accessories Compatible with STIHL 017, 018, 021, 023, 025, MS170, MS180, MS210, MS230, MS250 series Package includes: 1 × Sprocket, 1 × Clutch, 1 × Sprocket Bearing, 1 × Worm Gear, 1 × Washer, 1 × E-clip, 1 × Spark Plug Installation Installation and replacement work will be quick and easy, with each replacement part perfectly matching the original components.