The Hot Strip Mill (HSM) is where the massive slabs produced by continuous casting are reduced into manageable rolls of steel. The slab is reheated to approximately 1100°C to 1250°C and passed through a series of "roughing" and "finishing" stands. These stands use immense hydraulic pressure to squeeze the steel, reducing a 250mm thick slab down to a strip as thin as 1.5mm. In the tube industry, the HSM dictates the "gauge" (thickness) of the tube wall. The precision of this mill is paramount; if the strip thickness varies across its width (known as "crown"), the resulting tube will have an uneven wall thickness, making it difficult to thread or join in structural applications.