Clearfix screws are the newest in technology related self drilling screws for polycarbonate roofing.

These screws not only drill their own hole in the timber or steel supporting beam but they also pre-drill the polycarbonate with an oversized hole to allow for the sheet's expansion and contraction.

All other polycarbonate screws only pre-drill their own hole in to the supporting beams but not the polycarbonate sheets themselves which require this oversized hole.