SH-25 Set of Curved Steel Shims for Rekeying, Lock Picking
Shims are used primarily in the rekeying process, when keys are not available for a cylinder you have in hand. They are simply very thin pieces of curved stainless steel, preformed to fit the curve of a lock plug.
Slipping the shim underneath the top pins from the rear of the cylinder separates the top pins from the bottom pins and allows the plug to turn. This is done by using a key blank or a pick, lifting each bottom pin upward as a very minute amount of forward push is applied to the shim.
As the bottom pin reaches the shear line, the shim will work its way smoothly between it and the top pin, and you go on to the next pin stack, working from rear to front.
These shims are .0015 in thickness and are of the finest quality.