The Heavy Duty Seam Plates are specifically designed to be used for the attachment of UltraPly TPO Membranes to approved substrates. The plates are packaged in a clear plastic sleeve for easy handling. The sleeve has an easy-open pull tab with serrations that runs the length of the sleeve. These plates are to be used with Firestone Heavy Duty or All-Purpose Fasteners into 22 gauge steel, wood or structural concrete decks (Heavy Duty Fasteners only). They may also be used with Firestone Purlin Fasteners to attach membrane to structural steel purlins.