It protects up to three trombone moutpieces from light damage and scratches. I used to use it in my gigbag that didn't have a moutpiece holder, but now when I have purchased a new case I use this when I have to bring multiple mouthpieces to a gig, school, a masterclass or whatever the occasion may be. It sure does what it's supposed to, and is one of few mouthpiece pouches for trombone that fits up to three mouthpieces. (Large bore tenor)