Multimode.
I’m a snob, though.
What’s multi-mode?
2 lane highway
In the world of fiber transcievers, there are, in a broad sense, two types of fiber: multimode and single mode. The “mode” refers to how the waves of light travel through the fiber.
Single mode is capable of traveling longer distances and carrying more bandwidth. So, as an “over engineer,” I like to futureproof with insane overkill by running single mode fiber and using those transcievers. (as opposed to multimode, as this one is)
For most people, this device is more than adequate, but I wouldn’t personally go with it unless there’s already multimode fiber in place.
If you’re referring to the device using two fibers vs. one, that’s something different. When there’s only one fiber for both transmitting and receiving, that’s referred to as “bidirectional” or BiDi.
I am a total nerd. I hang my head in shame.