This simple 3D printed adapter changes any water bottle cage mount into a double.  The angle is set so that with two standard steel water bottle cages mounted, 2 water bottles will fit in between the crank arms on a standard 168 q factor MTB crankset.  This item will work anywhere a cage mount in available.  If one would like to also pruchase a King cage top cap mount, 2 water bottles can be easily and securely mounted on the top cap.  This is a convenient and safe placement for XC racers.  It is also a strong extra option for bike packers.