The 3-slot base with 4 threaded holes provides additional adjustment of up to 118mm and mounting options vs the B-RAD 2. A typical application would be to mount a bottle cage in the forward threaded holes with a B-RAD accessory tucked behind it. This mounts perfectly to triple bottle mounts on frames and forks. The B-RAD 3 includes a recommended zip tie, channels for the zip tie, and a foam pad for secure mounting