Motorcycle Fork Stem Mount Base with 1 TPU Ball for Stem Holes 12mm to 24mm Mounts 1 Inch Ball Double Socket Arm The ball base designed to fit into the cylindrical or hexagonal bore wall of motorcycle fork stems. Suitable for stem tube holes 12mm to 24mm in diameter. Package comes with two sizes of metal spacers. Small size spacer fit for tube 12mm to 15mm in diameter, Large size spacer fit for tube 18mm to 24mm in diameter. You can choose one size of the spacers according to the tube diameter for installation. It is not supported to use two spacers of different size at the same time. The metal motorcycle fork stem base included B size 1" TPU ball allows for connection to any B size double socket arm. PRE-INSTALL CHECK: Measure tube diameter, select and fit the correct spacer before installing the ball base. Support minimum tube depth 38mm. ANTI-THEFT DESIGN: The bolt head of the fork stem ball base has a specially designed screw groove, and the package comes with a special wrench for tightening or loosening the bolt. Adds extra security to equipment attached to this stem base. EASY TO INSTALL: After select and fit the correct spacer, install the ball base. Step 1, insert the ball base into the motorcycle fork stem tube. Step 2, use the special wrench included with the package to tighten the bolt of the ball base clockwise. Installation Complete. _x000D_