Aero water bottle set (comes with the Transition bikes!)
Prime Aero Time Trial Bike Bottle Cage Kit | Chain Reaction
Aero TT
Amazon.com : Bike Seat Water Bottle Holder | Includes One Bottle Cage | Road and Triathlon Specific Aero Design | Attach Bottle Cages (One Included) and Two CO2 Cartridges (NOT Included) : Sports & Outdoors
SOC16: FSA Vision adds clever aero water bottle options for triathletes, plus new wide-rim brake caliper - Bikerumor