ToolUSA Toolusa High Visibility Magnetic Post Level With Rubber Strap: TU2799 This post level is made of Durable Impact Resistant Plastic measures 3.5" X3.5" X 5.5" Ultimate for use on any type of post to check plumb and level in both planes at the same time! Four Magnets Inside To Cling To Metal Posts, pole or stringer. - High Visibity catches attention. Injection-molded acrylic vials - two level and one plumb - resist breakage.- 90 Degree bend level Levels are used in the building trades, engineering, surveying, and metalworking etc