This Gas Cylinder was used at the Springfield Armory from June 1943 to approx. May 1945 to help tight the Gas Cylinder to the Barrel with the use of a Saw Cut through the Front Sight Base. Scott Duff talks about them extensively in his book on the WWII Garand. Two types of cuts are known, straight and diagonal. We are offering a limited amount of these Cylinders and have them in Narrow Base and Wide Base, just use the dropdown box. These Cylinders have been USGI Gauged and are Good. The new DuLite finish is at 99% and they come with their original Stacking Swivel. Nice cylinder for the collector and the shooter who need to clean up that loose gas cylinder and get their Garand shooting accurate again.