The Mitsubishi FX5U-80MT/ES is the 80-point variant of the MELSEC FX5U series — a compact PLC with a built-in AC power supply and transistor (sinking) outputs. Weight is listed at 1.09 kgs, which is the figure that determines whether your existing enclosure or mounting plate will carry it without reinforcement.
The 1.09 kgs weight on the FX5U-80MT/ES is higher than the 0.91 kgs of the FX3G-60MR-ES, and the FX5U occupies a wider DIN-rail footprint than the FX3G series, so mechanical layout in the cabinet needs checking before you commit the BOM line.
Where it sits in the MELSEC family
The FX5U series is Mitsubishi's current-generation compact PLC line — it programs under GX Works3, not the GX Developer or GX Works2 used by the FX3G and FX3U families. If you're sourcing a spare for a live panel running an FX3G program, the FX5U-80MT/ES is not a software-compatible replacement even if the physical footprint were the same; the program conversion path exists but is not a no-touch swap. The 80I/O count gives you more density than the 60-point FX3G-60MR-ES peer but in a larger frame — if you're upsizing an existing FX3G-based design, verify your I/O mapping and terminal assignments in GX Works3 before download.