I think there must be some confusion with some about the Optima and the Magnum 257 radio - just because they look the same on the outside. The Optima uses two IRF-520's instead of the EKL brand ERF-2030's in the final stage if I'm not mistaken. I imagine that someone could add a RFX-75 to the Optima. The RFX is made by Magnum/EKL - both are part of the parent company - RF Limited. Optima is NOT a part of RF Limited. They look the same; but have two different companies issuing these radios.