The YX055 is an optional upgrade signal (outdoor) antenna for the YX500-CEL which replaces the omni-directional signal antenna with a higher gain directional antenna. This 18-element Yagi antenna provides enhanced cellular performance with your Wi-Ex product (YX500CEL). Maximum performance is achieved when the antenna is aimed at the strongest signal from your wireless provider. The YX699 is a perfect complement in setting the direction of the YX055 antenna.