Three original HIGEE LiFePO4 cells at 3.2V — 120Ah, 280Ah and 314Ah — all rated 1C maximum discharge.
A short list built for capacity. At 1C the three sizes behave the same way on current and differ only in energy, so the choice comes down to how much room the box has: sixteen cells in series make a 51.2V pack of roughly 6.1kWh, 14.3kWh or 16.1kWh.
Because all three share the same rating, mixing capacities in one bank is never a good idea — build each series string from a single size.