The MSL1209 from Massachusetts Bay Technologies is a RF Schottky Diode with Peak Reverse Voltage 4 V (Breakdown Voltage), Forward continuous Current 1 to 5 mA, Forward Voltage 0.25 V, Power Dissipation 250 mW, Capacitance 0.08 pF. Tags: Chip. More details for MSL1209 can be seen below.