Check the listing for details. HP 11708A Reference Attenuator – 50 MHz Low SWR – Cal for 8484A 8481D 8485D. Condition: Used. Listed at 79.95 USD. Designed for use with the following HP sensors:8484A ,8481D, and8485D. The 11708A is. Model:HP 11708A. HP 11708A Reference Attenuator (unit only). Frequency: Optimized for50 MHz only ; do not use at other frequencies.