This device can attach to your PF IR receiver, and control PF motors with high reliability.
You can control upto 4 receivers, by mounting it at a distance.
Using this controller you will be able to control speed, direction and braking/floating actions of PF motors connected to your IR receiver.
In order to use this with your NXT, you will need PF IR receiver.
The Red spacer bricks and the PF IR receiver are shown to illustrate connectivity and integration, and are not part of this controller.