Ensures surfaces are evenly horizontal or vertical Screw-on application Use the bubble as a leveling guide When the bubble is perfectly centered between the two lines, that means the surface is level Dimensions: 2-1/2' x 3/4' RV Designer E409 Bubble Level - Screw-On, 2-1/2' x 1-3/4' SKU: 1023.2944 UPC: 601320984096