This really helps me when I am doing flip turns with the snorkel. It allows me to focus on breathing out through my mouth so I don’t breath in water.

Never used one of these before, but my first time swimming with this clip it helped to avoid accidently swallow water which is something I've struggled with a lot in the past with coordinating mouth and nose breathing. It's pretty comfortable, and definitely stopped water from getting into my nose. I can take it off and wear it like a ring on my finger while swimming so I don't lose it as well, and it came with a small storage case. My only issue with this clip is that is kept wanting to slide off my nose. I'm not sure if that's because it's just not compatible with the shape of my nostrils or what exactly, but it was a bit annoying after a while. It's work great otherwise.