It's simply inserted into the back of the 2500/2520 "Traditional" fulcrum tremolo body behind the arm between the clutch screw and arm threads. Once installed, you tighten the "clutch plug screw" using a 5/64" Allen key to tighten the fulcrum arm swing.

Length: 0.0000 in
Width: 0.0000 in
Height: 0.0000 in
Weight: 0.100 oz
Packaging: 0.0000 kg
Units in box: 1
Parts by Make/Model > Kahler Parts > 25xx Traditional - Fulcrum