Profile Design T4 Aluminum Aerobar. Profile Designs have put their considerable knowledge of aerodynamics and ergonomics into the design of the T4 Aluminum Aerobar. Line up for your next time trial or triathlon bike leg with confidence that you'll be fully equipped to pedal fast against the clock. This clip on aerobar is part of Profile Designs' superb T series, and the high performance shallow ski bend extension provides a single neutral wrist angle with a low extension length for better aerodynamics. The extension itself is construction of aluminum and can be adjusted in length from 125mm to 275mm. Furthermore, there's an additional world of adjustability to fine tune one's aero position courtesy of the J2 brackets and F 19a aluminum armrests. And for maximum versatility, the aerobar's clamp is compatible with both 31.8mm and 26.0mm bars.