Hollow Set Drop-In Anchors are internally threaded expansion anchors. They are designed for anchoring in hollow substrates such as hollow-core, precast, and post-tension slabs. They can also be used in solid base materials. Concrete masonry blocks often have a maximum outer wall thickness of 1-1/2". During the drilling process, spalling on the back side of the wall often decreases the wall thickness, leaving only 1" or less for anchoring. The Hollow-Set Drop-in Anchor is designed to perform in this environment, where most conventional style anchors will not function properly.