The 28-37-06A from TX RX Systems is a RF Duplexer with Frequency 144 to 174 MHz, Band 1 144 to 174 MHz, Power 125 W, Insertion Loss 1.2 dB, Isolation 35 dB (Between Channel) / 75 dB (Per Channel). Tags: Rack Mount. More details for 28-37-06A can be seen below.