The lag shield anchor also called concrete lag screw shields, lag screw anchor, is designed for use in conjunction with a lag screw, it can be used in many materials such as concrete, brick, block or mortar joints. The anchor is made from Zamac, as a result, it's highly corrosive resistant. There are six diameters: 1/4", 5/16", 3/8", 1/2", 5/8", and 3/4". For each diameter, there are both short and long shields. The short lag shield anchor is used in harder base materials and the long concrete lag shield anchor is used in softer base materials. As the screw is inserted into the anchor, the anchor splits apart and expands against the base material. This expansion creates friction.