Perma-Chink Log Boss has a redesigned head for better counter sinking and a 5/16" hex head driver. Also, the wings have been brought back to reduce the friction between the wood and the shank and clear out the splinters created as the fastener pulls down into the wood. This reduces the torque required to set the fastener into place. Perma-Chink Systems specifically designed these fasteners for the construction of log and timber structures. Their 3" long thread provides the grip necessary for pulling even the most difficult logs into place while the larger shank diameter increases the overall strength and pulling power. Learn more about Perma-Chink.