The component [B] lets you use as many Hydra modules that you desire and fit within the track system. The tracks are great for multiple light systems keeping them all at the same height, but lets you space and orient the LED units right where you want them.
To build your HMS Multi-Light Mount, please choose the A+B+C components below:
A - AI HMS 2-Arm Kit or AI HMS Hanging Kit
B - AI HMS Tank Mount Rail 24"/36"/48"/60"/72"
C - AI HMS Hydra 32/64 Tank Mount Bracket