The paper suspension is pumped into the headbox of the paper machine. Via the hydraulically pressurized headbox it passes through a tapered cross-flow distributor and manifold, through the rectangular discharge opening, or slice, onto the screen. The outflow speed of the suspension is adjusted to match the speed of the screen by adjusting the pressure of the headbox feed pump. This means an accurate pressure measurement, with minimal turbulence created in the headbox is vital at this part of the process.