These are meant to be placed between the mic grill, and the capsule head itself. It should be a fairly tight fit, and you will need to unscrew the grill in order to put the ring in place.

I know that these will work on the ULX-D and QLX-D line of mics, and from what I've been told, they will work on the axient line as well.

Fits the SM58 capsule for sure, I can't guarantee that it will fit any other capsules, but my guess is that it probably won't.