Crain 979 Universal Welding Tip works with a 3,4 or 5 mm round welding rod, a half-moon (half-round) welding rod, or a triangular welding rod. It has an adjusting screw at the rod inlet to adapt the inlet to the various rod shapes. The grooved brass pressure roller is also adaptable to multiple rod shapes. The hot air inlet is sized to fit Leister or the Crain No. 960 Heat Weld Gun or previous model No. 980 Heat Weld Gun, as well as other popular models of heat weld guns using a 5mm pencil tip nozzle.