Denny Prokopos is usually good for a laugh. The young grappler is Eddie Bravo's first black belt in the 10th Planet Jiu-Jitsu system and the head instructor at 10th Planet San Francisco. He also grapples with MMA champions Gilbert Melendez and Jake Shields too. As a world champion submission fighter, we were pleased to hear from Denny on Twitter that he likes our Diamond cup's protective ability and that, like us, he has a sense of humor about it. Check out Denny at We love hearing from pro athletes and regular people who train alike, let us know, Diamond is here to listen!