I will preempt the next question if I may with "is it the same as a 4 pin fan extension cable"?
No because it's female to female. I will say, I'm not sure if the wires are crossed at all and if they're not, you could use PWM cables as extensions to the female to female aquabus cable but I'd rather wait for a confirmation from AC.
Some MPS devices need the 5V power supplied by the 4th wire on the 4wire Aquabus cables but the USB D5 does not. It works just the same with the 3 wire Aquabus cable as it does with the 4 wire.
The Aquabus cables are the same as fan cables. Any fan extension can be used to extend and any female to female fan cable can be used for connections.