The 600 Grobeam strips fit onto TMC MMS rails and then with the TMC T8 end cap adapters will fit straight into the existing tube holders on the Roma 125 (which I have).
Word of warning, the lights end up being extremely close to the surface of the water so budget for a TMC Aquaray Controller (the basic approx £70 controller does the job perfectly) as you are unable to lift the lights up or down to adjust intensity when installed in the hood.
I'm using as much gas as i'm prepared to and have good flow/EI ferts etc and find that 60-70% max output is about all I can use before running into issues. Best to start around 25% output and work up slowly from there, all just my opinion (and experiences) of course... 🙂