The ML4673 from Spectrum Control is a RF PIN Diode with Insertion Loss 0.7 to 1 dB, Isolation 20 to 25 dB, Reverse Current 10 uA, Breakdown Voltage 500 to 550 V, Thermal Resistance 20 to 25 Degree C/W. Tags: Chip. More details for ML4673 can be seen below.