Stabila 80A-E-30cm Electronic Level uses audio angle guidance system with three different signals. You can align items without looking at the vial. The easy-to-read digital display - automatically rotates for overhead measurements. Features 1 horizontal vial. Reference angle mode allows you to take an angular measurement, store it and transfer it to other components. Available units are degree, percentage, mm /m and in/ft. With its light metal rectangular profile, its perfect for your tool bag. Vial measuring accuracy: in the normal position 0.029° = 0.5 mm /m, overhead measurement 0.043° = 0.75 mm /m.Electronic inclination accuracy: at 0° and 90° = ± 0.05° , from 1° up to 89° = ± 0.2° . Length: 300mm (12 in).