This quality precision machined adapter allows you to use any device threaded 5/8-24 to fit 9/16-24LH(Left Hand) threads. This adapter is threaded 9/16-24LH on in the inside (female threads) and has 5/8-24 threads on the outside (male). It is machined in one turning operation to guarantee concentricity to your threads. Full engagement flats for easier removal and disassembly. Imitation adapters often have very tiny wrench flats which can round off and become useless. Black Oxide finished. Engraved. The best price and quality for a 9/16x24LH to 5/8x24 thread adapter in the world.