The Sitero Expert Gel adds an extra layer of comfort to the Sitero shape, making it the perfect option for long distance rides in an aerodynamic position. And to further ensure strength and durability, it features hollow titanium rails and SWAT mounts for seat bag storage options. Features Next level comfort for riders of all sizes while in the aero position. Lightweight and supportive PU padding for comfort and support on longer rides. Durable and lightweight hollow titanium rails. High-frequency, welded cover material for secure hold and a smooth pedal stroke. Integrated Direct Mount Reserve Rack included for bottle/equipment storage solutions. Level 2 padding Medium density foam for bike feel with additional cushioning. SWAT -compatible mounts molded into the saddle base allow for sleek and integrated storage solutions. One size.