Machine Screw Anchors perform well in a variety of concrete strengths and can be used in brick, block or stone. They adapt well to hole size variations and can easily be removed, loosened and re-tightended, if necessary. Any screw head style can be used. To install the anchor, drill the appropriate hole size in the substrate and drop the anchor expander side down into the hole. Place setting tool over the anchor and hammer until set. These anchors are not recommended for use overhead or applications where holding values are critical.