Thermo expansion washers with foam gasket are the best solution for fixing polycarbonate sheets to a structure. The large surface area ensures the polycarbonate sheet will not be damaged under forces such as wind and snow load by reducing pressure points which may occur with a smaller washer. 

Another advantage of the thermo washer is it allows for expansion and contraction of the multiwall sheet which occurs during changes in temperature and also ensures no leakages occur at the point of entry. The cap ensures that the screw will be protected from the elements and prevent rust.

Specification

39mm x 8mm (W x H)