Model Compatibility: Fits MS250, MS230, MS210, MS 250, MS 230, MS 210, 021, 025, and 023 chainsaw engine models as specified in the title. Technical Specification: Includes a 42.5mm cylinder and 40mm piston with matching crankshaft, maintaining dimensional specifications stated in the title. Component Inclusion: Contains cylinder, piston, and crankshaft as a complete kit for chainsaw engine rebuild or replacement purposes. Functional Purpose: Designed to restore engine when replacing worn or damaged cylinder, piston, or crankshaft components. Installation Scope: Intended for use in the engine motor assembly of compatible chainsaw models listed in the title only.