i would have to agree with a lot of what was said. i love the control and humiliation factor of being in one but they are definitely not for the inexperienced. One with a rubber or leather cover is a lot easier on the teeth especially for anything beyond a short session. Although your lips cover over the ring if it's in tight it doesn't help much when you're giving a blow job, your tongue and throat have to do all the work. It is a little more difficult since you have absolutely no control over what is put in your mouth and how rough/deep it is put in.

While they can be worn for long term they really make your mouth tired/sore and are really messy to sleep in from a drool standpoint.