Park Tool Pin spanner with 3 mm spline

Spanner from Park Tool, used to make sure that the bottom bracket isn't turning when dis/mounting many older bottom brackets.

3 mm.

Park Tool Pin Spanners have been designed to give maximum usefulness and versatility at the lowest possible cost. Tough, high carbon tool steel is used on each tool to ensure long life. Handle is vinyl coated to give a good grip. Each Pin Spanner is color-coded for easy recognition.