GTMAT GT Seam Tape Aluminum Finishing Tape Automotive Sound Dampening - Sound Deadening Installation Includes: 3in Wide 100ft Roll of 4 Mil GT Seam Tape 100 In Length 3 Wide 4 mil Thickness Aluminum Tape With Release Liner Use GT Seam Tape to cover seams from your GT Mat installation creating one solid piece of sound deadening material. GT Seam Tape also makes a complete finished look to your installation.