Collet wrenches grip collet nuts and provide leverage to tighten or loosen the nuts when installing or removing collets from machine tools. Their jaws fit specific collet styles and sizes.

The key is to fully engage (clip in) the collet inside the nut before you tighten it onto the holder. When properly seated, your collet face should be flush with the face of the nut - almost press fit into the nut. At that point, you're ready to place your tool into the collet and tighten things into the holder.