The Keysight 11583C contains a set of four 8493C attenuators 3, 6, 10, and 20 dB furnished in a handsome walnut accessory case. The Keysight 8493C are APC-3.5 connectors with a maximum frequency of 26.5 GHz. This set is ideal for calibration labs or where precise knowledge of attenuation and SWR is desired.