Prologo Zero Tt-Triathlon Saddle With Nack Carbon Rails Prologo's Zero TT is an ideal saddle for medium and short distance high intensity riding where a frequent change in position is necessary. The flat shape in conjunction with the rigid saddle shell causes a very direct ride feeling. Nack Carbon rails. Specifications Dimensions - 258 x 134mm Carbon Fibre Injection Nack Carbon Rails Microfibre Cover Light Foam Padding Weight - 230g