The only purpose of this adapter is to replace the top of an already existing HyperStar adapter to change its thread type. An example of this is if you have a ZWO 294MC pro with M42 threads, and you bought a ZWO 6200 Pro with M54 threads. Each camera has the same backfocus but the threads to attach it are different. This saves you the cost of buying a second adapter when you only need a different thread. All other adapters for the HyperStar can be found here.