Converts 5/8" male to 17mm female. Also, by reversing the position of the set screw and the T-Handle, can be semi-permanently attached to any snap-in accessory (i.e. Hollywood Superflex, Microphone Adapter, Right Angle Snap-In). For use with 5/8" male mounting such as a Matthellini Clamp, Nail-On Plate, or 5/8" stand top, etc.