Classic Flat shape that has always distinguished the Flite family, combined with the more compact design of the Boost geometry- TI 316: 7mm rails are hollow titanium, a balance of strength and light weight- Manganese: 7mm rails made of a Manganese and CrMo alloy for excellent durabilty and value- Fibra-tek: Selle Italia's latest cover material offering supreme durability and comfort- Soft-Tek: Polyurethane cover for high levels of comfort and durability- For more information on idmatch visit http://www.selleitalia.com/en/idmatchsystem/- L3: "Wide" intertrochanteric distance and high pelvic rotation (Flow and SuperFlow saddles)- S3: "Narrow" intertrochanteric distance and high pelvic rotation (Flow and SuperFlow saddles)