ALLIGATOR anchors are designed to hold high-loads in solid walls, ceilings and floors but also hold securely when they encounter an unexpected cavity, such as in hollow brick or hollow block or even in drywall or, especially, in tile over drywall. The specially formulated polypropylene body flows into and locks up with any undercuts in the hole, bonding the screw to the wall and sealing the hole to prevent moisture from entering. Optimal holding values [measured in tons] are obtained in highly dense substrates by using a screw diameter and a drill diameter of the same size as the anchor diameter. The anchor is available both unflanged for pushthrough mounting and with a flange for use where a cavity is anticipated (drywall, hollow brick).