Stainless steel specification

1.2 X 4 X 2500 means:

Thickness X Width X Length

1.2mm thick X 4 feet (1219mm) X 2500mm

This is not a national standard. It's a fixed-foot board.

4 feet (1219mm) 8 feet (2438mm) 10 feet (3048mm)

The national standard is 4X8

4X10

4X3.5m

4X4m