This aluminum I-beam spirit level features three vials: a 180° vial and two 90° vials. It has easy-to-read graduation marks on the top side, starting from zero cm in the middle and extending both left and right. The vials are UV and shock-resistant, while the rubber end caps provide added protection if the level is dropped. There are hang holes at both ends for easy storage. The accuracy is 0.5mm in a standard working position.