Aluminum foil seal tape is the solid tape that seals the top edge of twin-wall polycarbonate panels. It caps the open flutes vapor-tight, keeping water, dust, and insects out of the channels so the panel stays clear and insulating.

Each roll is 1" wide by 150' long, made by Gallina USA, and fits 8mm twin-wall polycarbonate. Apply it to the upper edge, then fit an edge profile or U-channel over the tape to hold it and protect it. It's the top-edge half of a two-tape system: pair it with breathable vent tape on the bottom edge so trapped moisture can drain. Also sold as top sealing aluminum tape or solid polycarbonate seal tape.