Standard frame-mounted bottles have high aerodynamic drag, so place your bottle at the rear instead. The Delta 220 mounts on the saddle rails for no measurable drag. The Delta 225 was specially designed for ISM Adamo saddles with a transition hook. The system includes a Gorilla XT carbon cage which provides a tight 14-pound grip on your bottle. Mounts to most standard metal-rail saddles. For carbon rails, purchase the optional Delta Adapter.