The Xantech 28DES is a black (IR opaque) 1" x 2" shield that fits over both the Xantech Designer Emitter body and the IR sensor window of a controlled component. An optional accessory, it prevents unwanted external IR signals frompassing through it or leaking past it. </p><p>The 28DES also prevents IR from the Designer Emitter from radiating backwards into the IR sensors of other components. It is especially useful for zone controlled applications where you want the equipment controlled only by the Designer Emitter fastened over the component IR sensors.</p>