Power Custom's Keith #5 Base Pin is designed for large frame revolvers such as the Ruger New Blackhawk, Vaquero, Super Blackhawk, and Bisley 2.875". The base pin is a handsomely finished hardened steel with a ground to .2495" diameter. Locking pins have an allen set screw in the head to hold the pin in place against recoil. Installation instructions are included and on most guns these pins drop right in. Notes:Ruger (3 screw) Old Models use the same base pins for all corresponding frame sizes. You can use the New Blackhawk (longest) and shorten to length. The spring loaded plunger is not needed. The last number is the maximum length measured from under the head to end the base pin, not the plunger.