Screw anchor expander | Thread size 3/8-16 | Construction hardened alloy steel | Application, for setting caulking screw anchorsAmazon.ca Product DescriptionGreenlee's screw anchor expander quickly and securely set expansive screw anchors in masonry, regardless of thickness. Made from hardened alloy steel.From the ManufacturerGreenlee's screw anchor expander quickly and securely set expansive screw anchors in masonry, regardless of thickness. Made from hardened alloy steel.