Contractor Top-Read Aluminum Level, 3 Vials, 24-In.Johnson's 3700 I beam level was designed to be durable and easy to use so much so that it has been the standard in the industry for over 30 years. Its heavy duty aluminum frame ensures accuracy and is durable enough to withstand even the roughest jobsite abuse, and that frame is protected by shock absorbing end caps if the level is accidentally dropped. The level also comes equipped with replaceable, durable acrylic vials that are impact resistant