Double-sided bottom bracket lockring hook spanner. One side is a single hook, the other is a hook spanner with 3 notches for better engagement in the lockrings. The three-hook end will fit 3-notch lockrings with a maximum outside diameter of 46mm, & minor diameter (in the notches) of 40mm.
HCW-4 Features Center to center measurement between pins is 29mm. Pin diameter is nominally 2.3mm.