To cross the raised areas of corrugated metal roofing, use the SnapNrack 232-02421 Corrugated Roof Block. This prevents the roof profile from being crushed when mounting an L-Foot (not included) with the penetration at the highest point of the roofing material. Can be fastened to a metal purlin with a tek screw or a wooden rafter with a lag bolt. To close the hole in the metal roofing material, sealant must be used.