NPL require a RF cryogenic probe station with four installed RF probe arms. The system must support cryogen-free operation using a closed-cycle refrigerator. The base temperature must not exceed 5.5 K, and the temperature must be controllable from 6 K to 350 K. The system must support RF measurements from DC to 40 GHz using ground-signal-ground (GSG) probes. The system must accommodate samples with a diameter of at least 2 inches. Vibration at the sample stage must be less than 1 micrometre. The system must include all necessary components, including a turbomolecular pumping system, a microscope with a zoom ratio of at least 12:1, probes, and a calibration substrate. The supplier must install and verify the system and provide user training.