The Johnson Level 24" Heavy Duty Magnetic Aluminum Level is designed with a strong holding magnetic edge allows that hands free use on ferrous metal surfaces. Oversized 1/2" diameter vials are easy-read. Heavy duty aluminum frame Job Site Tough™. Ergonomic cushioned hand grips. SurroundView® vials reflect ambient light for easy-read. Top-read window maximizes readability. Field replaceable cover plates and vials. Shock absorbing end caps protect frame.