The 2031-90-A from CPE Italia S.p.a. is a RF Surge Protector with Frequency DC to 2.5 GHz, Insertion Loss 0.2 dB, Operating Temperature -40 to 100 Degree C, Operating Voltage 900 V, Surge Current 5 kA. Tags: Gas Discharge Tube. More details for 2031-90-A can be seen below.