The Selle Italia SLR has long been a favorite for the racing crowd due mainly to its very light 145 gram actual weight combined with show-bike slim lines. Many of us have used the SLR at one time. TT in this case stands for "tubular titanium" not "time trial". The tubular titanium rails help save grams and are the standard 7mm round size and compatible with virtually any seatpost. A carbon injected fiberglass shell is both very light and rigid for solid support. Firm EVA bio foam padding delivers a little cushioning for a dose of comfort.