HIGH QUALITY - The wood screw is made from a hardened and strong screw head, it will not strip when the screw meets resistance. No one sheds their head when sinking. The screws are smooth: No pitting or irregularities. Clean threads. EASY TO USE - Concrete screws that screw directly into pre-drilled pilot holes. It is very durable, does not deform or break easily. After installation, it has good fixing power. No anchors or plugs are required. BENEFIT - Heavy duty screws are very strong and are perfect for securing window and door frames into masonry or concrete walls. p> ZINC PLATED ALLOY STEEL: Material commonly used in generally dry environments. Zinc plating provides temporary protection against rust, but once it wears away, the steel will rust. UNIVERSAL USE - They have a very high pull-out rate and can also be used with lids. Screws for fixing window and door frames to screw into a masonry or concrete wall. Recommended screw diameter: 6.5 mm