Yes, that is what you need. The MRFB is the "i" version, which runs on the 433 MHz frequency. You would need an "i" remote to communicate with it, which you do not have. Since they are discontinued, they me be a challenge to find. They work great though if you can find one.

**I will add I never integrated lighting with an MX-800, so someone will have to chime in if it is not compatible with the lighting for some reason. To my knowledge it will work though.