Tough genuine Shimano tools constructed of hardened steel for longevity & durability. USAGE For removal of cotterless crank arm Installation & removal of front chain wheel for square bottom bracket with 14 mm fixing bolt USP Internal puller can be rotated with 15 mm wrench 14 mm hex or 8 mm hex wrench Hardened steel for rigidity & durability Compatible with both OCTALINK & square bottom bracket