The ML4646 from Spectrum Control is a RF PIN Diode with Forward Current 10 to 40 mA, Reverse Current 10 uA, Breakdown Voltage 400 to 450 V, Thermal Resistance 15 to 20 Degree C/W, Forward Resistance 0.6 to 0.8 Ohms. Tags: Surface Mount. More details for ML4646 can be seen below.