Never had to order Fiber before - I'm looking for something to connect a 100 GBASE SR10 with a 40 GBASE SR4. Only thing I know is I have an MTP LC module\cassette but I don't even know if I need it.

These are two arista devices, both operating at 40G. It's literally just one circuit but the only thing I'm going off of is the CLI and my outdated and spotty knowledge of fiber in general.

I don't need a breakout cable do I? The MTP cassette makes me think I do but they're both singular ports on the devices-with some logical interface config. I only know I need OM3/4 and LC.