Another great MINDSTORMS NXT accessory for experienced programmers! Add an NXT-G program loop that needs a specific transponder to run. When you have the key transponder, only you can start the program -- use multiple transponders to run multiple program paths! Includes sensor and 2 RF transponders! Does not include connector cable. This is the individual component, and does not include the NXT Intelligent Brick, software or any accessories. It requires the complete LEGO MINDSTORMS NXT set (#8527) for use.