Please note: A few types of harmonicas (stainless steel, aluminum, plastic etc.) won't work in HarpLock. Pease test your harp with a magnet before you buy. HarpLock is designed for the Shure SM58 and Shure Beta 58A but also fits similar microphones with a maximium grill thread diameter of 1.290. (Almost 1 5/16") Questions? Call Gary 317-782-9948.