The 53K38R-MSON3 from Rosenberger is a VNA Calibration Kit with Frequency DC to 8 GHz, Max Input Power 1 W, Operating Temperature 0 to 50 Degree C, Return Loss 35 to 42 dB, Storage temperature -40 to 85 Degree C. Tags: Passive Calibration Kit. More details for 53K38R-MSON3 can be seen below.