Anchoring in hollow masonry requires the use of perforated sleeves. During installation a sleeve is placed into a hole and it is entirely filled with anchoring resin. Once a fixing is introduced into the sleeve, it drives the resin out through the perforations and into the cavities of the hollow masonry. The cured resin then becomes stronger than the hollow material and locks the fixings from the inside. If properly installed, the substrate will always fail before the resin or the fixing.