Two measuring. The top is made from two plates. You are bumps Bridge of wood and masonry. Inserted on the squares you can take two spacers. It allow for measurements on highly uneven surfaces for passenger cars. Light metal rectangular profile with 2 vertical levels and 1 horizontal Bubble. Accuracy of measurement: in normal position 0.029 ° = 0.5 mm/m, fully extended in normal position 0.057 ° = 1.0 mm/m, overhead measuring (when closed) 0.043 ° = 0.75 mm/m. Article number 17709.