Profile's Aquarack holds 2 water bottles behind the seat where they are tucked out of the wind for superior aerodynamics, and are also easily accessed. Plus, there are CO2 cartridge mounts as well. The Aquarack clamps tightly to seatposts from 27.2mm to 31.6mm in diameter.
It has a slick design, and mounts in less than 2 minutes to your seat posts. The problem is you lose your sports bottles while riding (even on city streets)since the cages' grip on the bottles loosens its grip even with a casual ride. Unless you are willing to constantly push back down on the sports bottles while riding or replace lost bottles, I do not recommend. The building material is cheap and broke.
Bottom LineNo, I would not recommend this to a friend