This product is designed to let you put ONE or TWO water bottle cages behind your bicycle saddle. Triathlon style. With this saddle mount bottle cage adaptor, you can make it DOUBLE or SINGLE setup depends on your need. Beautifully CNC machined from aluminum. It is strong, sturdy, and has a high-quality feel to complement your nice bikes. The angle of the bottle cages can be adjusted. The bottle cages can be adjusted to the perfect angle for you to pull out and put in the bottles easily. This bottle cage holder can also be used as a GoPro camera mount. The part that designed to let you adjust the angle is made to the GoPro standard, so, instead of attaching a bottle cages, you can attach a GoPro Camera to this saddle mount. The base of this adaptor is also adjustable. It will fit almost all bicycle saddles with rounded metal rails in the market perfectly. It can also be installed in different areas of the rails. If you look at the pictures carefully, you would notice the base is mounted on both the lower section and back section of the saddle in the pictures. Water Bottle and Bottle Cage are NOT included. WILL NOT fit extra beefy MTB Saddle Rails as Some MTB Saddles have extra beefy 9mm rails. WILL NOT fit carbon rails. Do not use it on the saddle with carbon rails.