The Hewlett Packard HP 779D Directional Coupler is a device used for measuring the power of a signal travelling in a specific direction. It has a frequency range of 1.7-12.4 GHz and a mean coupling of -20dB. The product is manufactured by HP and comes without cables or any other accessories. It falls under the category of Other Test, Measurement & Inspection equipment and is suitable for use in business and industrial settings.