The difference between these two versions of HoverBar Duo is the ease with which the arm can be moved between the weighted base and shelf clamp.
HoverBar Duo (1st-generation) comes with a hex key to disassemble the arm from the base, then assemble it onto the clamp (and vice versa). This version is appropriate if the HoverBar Duo arm won’t be moved regularly.
HoverBar Duo 2nd-generation has a QuickSwitch mechanism to quickly and easily release the arm to switch between the base and clamp. This version is recommended if the HoverBar Duo arm will be moved regularly.