Rash guards serve their primary role as a barrier between skin to skin or skin to mat contact when you’re training. Rash vests as very popular items in MMA and BJJ gyms around the world.  A good quality MMA rashguard will stand the test of time whilst helping to stave off some of the infections that crop up in gyms occasionally, and it will also help prevent mat burn. Mostly worn for training either on their own or under a Gi