Profly goaltenders tend to have an easier time "skating" on their knees, also known as the "backside push", or the "butterfly slide". This term describes where one leg is down, and one is up. The goaltender pushes with his/her leg up laterally from the heel, laterally toward the down leg. This allows for a slide from the up leg to the down leg without getting off the ice completely. If a goaltender is on the inside corners or if the pad faces as in non-progressed "butterfly" styles, the push results in a tendency to roll over onto one's chest and belly.