The ML4631 from Spectrum Control is a RF PIN Diode with Forward Current 10 to 100 mA, Reverse Current 10 uA, Breakdown Voltage 200 to 250 V, Thermal Resistance 12 to 15 Degree C/W, Forward Resistance 0.5 to 0.7 Ohms. Tags: Surface Mount. More details for ML4631 can be seen below.