These forgefix double slotted roofing bolts are supplied with square nuts and have a low profile mushroom head their bright zinc plated finish increases resistance to corrosion the bolts are therefore suitable for both interior and exterior use and can be exposed to weather conditions without the risk of rusting applicationused in many applications other than roofing when joining products together use clearance drill sizes 1mm larger than bolt diameter zinc coatings prevent oxidation of the prot