Aluminium foil tape is used with a Multiwall sheet. The foil tape is generally placed on the upper end of the sheet and is hidden / not exposed to the elements. It is used where the top end of the sheet is going in under the eaves of the house or structure.

Micron thin tape that is 25mm, 38mm, or 50mm in width and 50mtrs in Length. One side is foil silver; the other side is hi-tack adhesive.