The frame of the 81S is an aluminium pressure die casting with the reference face carefully milled. Both vials can be used normally or upside down. The ends of the level have protective noses to prevent the reference face deforming due to shocks. Its bevelled shape makes it suitable for working in cramped spaces. It features one vertical and one horizontal vial for normal and upside down measuring. Accuracy: 0.5mm/m normal position, 0.75mm/m upside down position. Length: 25cm (10"). Supplied complete with holster.