Cymbal muzzles are rings of 1/8" Mass Loaded Vinyl (MLV) of various widths. A 3" ring will almost completely deaden a cymbal, but a 1/2" ring turned an obnoxiously overbearing 22" ride cymbal into something I can live with. Before putting the muzzle on, it would drown the whole kit. Now it doesn't run away.
MLV can be cut with ordinary scissors. Less is more, to achieve the subtle effect of "reining in". Too much and you have a cymbal silencer! Cut the inner diameter just slightly bigger than the bell of the cymbal, so your ring won't slide around. Experiment with widths. Just a half inch can have a DRASTIC effect on a smaller cymbal. Experiment, and have fun drumming!