RV Designer Bubble Level Two Way 2 1/2in x 1 3/4". Use the two bubbles as a leveling guide. When the bubbles are perfectly centered between the two lines that means the surface is level. If the bubbles are closer to one line than the other then the surface is not level. The E411 model measures two ways at the same time: horizontal and vertical. The dimensions of this level are 2-1/2" by 1-3/4". Each package includes two two-way levels and mounting screws. Features of RV Designer E411 Bubble Level Two Way 2 1/2in x 1 3/4" Ensures surfaces are evenly horizontal and vertical Levels two ways at the same time: horizontal and vertical Use the bubble as a leveling guide When the two bubbles are perfectly centered between the lines that means the surface is level Dimensions: 2-1/2" x 1-3/4" Package Contents: RV Designer E411 Bubble Level Two Way 2 1/2in x 1 3/4" RV Designer E411: Bubble Level Two Way 2 1/2in x 1 3/4"