BBB ´´AdaptRail´´ bottle cage shifter attachment.Versatile rail mounting system for bottle cages and accessories.Reposition your bottle cages for easy access and efficient use of frame space.Attach AdaptRail accessories such as a StrapPlate or DualMount.Sizes M and L accommodate one bottle cage and one StrapPlate.Size L holds two bottle cages one above the other.AdaptRail.Reposition your water bottle holder to make better use of available space.Sometimes you can come up with an idea that turns out to be better than the one your bike designer came up with.The AdaptRail lets you transform your bike the way you want.Attach the AdaptRail to your bike and adjust your bottle cage to make better use of the space available.You can also attach the StrapPlate or DualMount for an infinite combination of possibilities, and your bike will fit like a glove!.