Fasten Up screw bolts are high-strength concrete and masonry screw anchors with helical threads that, when tightened, allow the bolt to cut its own thread in the concrete and masonry. Since these anchors don\’t expand and no plugs are needed, they are perfect for use in concrete and masonry where cracking may be an issue.For internal and external bolting and fastening of engineering and construction components where authorised anchors might not be needed, our galvanised roundhead concrete screw bolt contractor line is made to provide a visually appealing end product and a non-intrusive, non-trip hazard anchoring option.