1/4-20 x 4 Hanger Bolt Fully Threaded Zinc Plated . Bolt with threaded areas at both ends--lag screw thread at one end and unified thread at the other. 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 its blunt tip. Designed to hang material from wooden structures. The lag is wrenched into the wood and the assembly is completed after applying a nut. Used for suspending electrical wiring and sheet metal. Also common in the furniture industry.