Selle Italia SLR Boost TM Saddle - Manganese Black S1. The SLR Boost TM saddle marries modern technology and saddle ergonomics to the popular SLR design. It shares the same design and molding as other SLR Boost saddles but at a fraction of the price thanks to the utilization of manganese and chromoly TM rails and a Soft-Tek polyurethane cover. The traditional central fill with an indented central channel to allows for pressure-relieving comfort.