The Alpha One is compatible with the p5-3 and p5-6. On the p5-6, the front fairings may not work with it or will require some modification to fit. The Alpha One is fully compatible with Cervelo p2 and p3 models, regardless of year. The Alphe One is fully compatible with the P-series.  The Alpha One is NOT compatible with the P5x, P3x, PX, or P5disc.