We just got in some of the Lee undersize 40 S&W from EGW. These are used to get the bulge out of rounds that have been fired from Glocks. Use them as any other die, they are cut down to get futher down the brass allowing you to get the "bulge" out. This way you can use this brass an anyother firearm. I and several others have been using these dies for years and it is a great alternative to having your brass rolled sized.