The Serfas EX-RX Exerciser On Rails is designed for use as a stationary bike exercise saddle. Features a comfortable gel top layer, progressive foam technology, Deep Groove Design, durable sweat proof vinyl outer cover, central Pressure Eliminating Channel, Zero-Friction Gel Infused Padding, Twin Bar Anatomical Flex, I.C.S. Infinite Comfort System, Dual Density Base, and Press Reducing Two Step System.