Quite often Triathlon framesets have smaller frame triangles and shorter head tubes in an effort to make the frames more aerodynamic. This results in having to pull the water bottle somewhat sideways in order to get it out of the bottle cage. Most current cages on the market make bottle extraction difficult.
The engineers at XLAB have a cage that grips very well over bumpy surfaces but also has a special cut off angle of 30 degrees which testing has proved is the optimum angle in Tri framesets. It is super quick to get the bottle out of the cage.
The cage features stiff bottom lip to support large bottles, stiff upper tab to retain bottles in the cage and slots in the back to provide vertical adjustment on the frame.