Both side view & top mounted glass vials. Made with a strong aluminum I-beam. Finest select wood sides are inlayed to give a warp-free light weight mason level. Features 2 top-reading yellow no fade vials; grade marks show 1/8"variations. Levels block in two directions at once. A notch for getting over interlocking tabs. Patent #US 8,011,108 B2
Levels block in two directions at once
A notch for getting over those interlocking tabs
Made in the USA