The Orbital MT25/40 is a Bias Tee (and a Diplexer, and a Mux Tee...)

Orbital MT25/40 Mux Tees function as Bias Tees (inserting DC power into the combined signal), as Diplexers (inserting 10 MHz into the combined signal), and as Mux/Tees inserting both DC power and 10 MHz reference). 

The MT25/40 will also act as a DC block on the combined input port - thus allowing DC to be inserted.  It can also act as a low-loss impedance transform, depending on which connector combinations are chosen.

MT25/40's also work in both directions - in reverse position they can extract L-Band or 10 MHz signals. 

The MT25/40 has less than 0.5 dB of insertion loss and filters and conditions its incoming signals.  It is the fundamental component of Orbital's signal routing solutions.