ISM PS 1.0 - BlackUtilizes our Performance Short shape chassis. The PS 1. 0 is a true performer and remains our most popular model for triathlon. It features minimal 15 series padding and sloped front arms, reducing superficial chaffing. The PS 1. 0 features a slight upward slope at the rear providing superb hip support when your hips rotate forward in the aero position. This tends to be preferred by athletes who dont move around on the seat excessively while riding.