They are always matched with a saw machine.
They measure the length of the profile that is going to be worked, to ensure that the cut complies with the quota specified in the drawing or order. It consists of a motorized carriage that moves perpendicular to the cutting axis, on a guide, thanks to a rack-and-pinion system.
The gauge moves to the set cutting quota, controlled by an encoder. Correct measurement is guaranteed by an electrically insulated plate, which signals when the semi-finished piece is resting. A slow-down system is provided to allow for the sweetest possible beam-to-plate contact.