The Arione CX Kium rail saddle is the latest version of our most popular saddles. It is about 30 grams lighter than the previous version with a slightly slimmer profile. The rails are made with a special "Kium" alloy that uses silicon and chrome to delivery lighter weight and better damping compared to titanium. The Arione uses Wing Flex technology for a saddle shell that is stiff yet flexible for optimal performance and comfort. Many of us find the unique flex of the saddle really allows the rider to power through the pedal stroke and help provide a smooth pedaling action. The Arione is ICS compatible meaning a Fizik ICS saddle bag can snap onto the saddle for a super-clean installation--no more straps flapping around.