The Slim-Line Gun is another form of collet extender, and can be preferable above the others. The Slim-Line Gun is a fully self-contained, self-triggering CD weld gun. This gun plugs directly into the welder and requires a "B" Collet. To operate, load the stud into the collet, locate the gun in place, and then press the stud against the base material. The weld will take place automatically, and firing occurs only upon proper pressure.