Back caps cover the back portion of the electrode on a TIG (tungsten inert gas) torch to prevent the tungsten electrode from shorting out during welding. Sometimes called end caps, they also put pressure on the collet to keep the electrode in place in the collet and create a seal that prevents shielding gas from leaking out the back of the TIG torch. New electrodes require long back caps. As the electrodes grow shorter from use, shorter back caps can be installed on the torch to improve access in tight areas. A complete TIG torch setup includes a nozzle, collet body or gas lens, collet, insulators, back cap, torch body, torch handle, and tungsten electrode.