Hanger Bolts are threaded at both ends. One end is a lag screw thread, the other end has a bolt thread. Standard hanger bolts are designed for insertion into a predrilled pilot hole. The end of the wood thread is designed as a taper which is threaded all the way to it's blunt tip.
These are designed to hang material to wooden structures. The lag is wrenched into the wood and assembly is completed after applying a nut. They are used for suspending electrical wiring and sheet metal. Also common in the furniture industry.
