Designed to be used with our LED eyes, the 9V Battery Eliminator gets rid of the need for 9V batteries. Now you do not have to worry about buying 9V batteries over and over again, wasting money that could be used on other props. Another advantage is the convenience of having the LED eyes plugged into a power strip, where all that's needed to turn them off is the flick of a switch, instead of having to disconnect the battery from the snap.  Also, this simplifies integrating LED eyes with prop controllers because you can wire the 9V Eliminator through the controller and not need to worry about battery consumption while the controller is inactive. At $9.99, it won't take long for you to recover the cost from all the batteries you will not need to buy.