This is an used Vertex 4 port C-Band Diplexer, Model 106824.
What makes this C-Band Diplexer special, is that it can be converted from linear polarity to circular polarity with a minimum of effort. Traditional feeds are either circular, or they are linear polarity and to change from one polarity to the other entails removing one feed and then installing the other.
Having a dual polarity C-Band feed saves the teleport operator time and money.
The frequency range of this OMT is:
RX: 3.825-4.200 GHz
TX: 5.850-6.425 GHz