These thin inserts are designed to use with the Aficionado banger by Scientglass. The Thimble has a little bar in the middle for easy removal with any dabber. The Thimble is meant to be used as a heat transfer. The heat from the nail transfers to the Thimble and keeping it at a nominal temperature. The Thimble holds a lower temperature longer because the nail is constantly trying to transfer its incredible heat over to the nail. The temperature of the Thimble stays constant at a lower temperature than the nail’s outer surface.