MAGNETIC LEVEL: The leveler features a strong holding magnetic edge that allows hand-free use on the ferrous metal surface for added convenience. QUALITY CONSTRUCTION: The carpenter's level features a heavy-duty aluminum frame that promises to withstand the harsh impacts at the job site; delivering unparalleled performance. ACRYLIC VIALS: The magnetic box level features easy-read replaceable acrylic vials made of impact-resistant material for maximum durability. SMART DESIGN: The aluminum box level has a top-read window that maximizes readability; allowing you to access reading from any angle. USER-FRIENDLY: The 18 in. I-beam level has replaceable cover plates and three vials that make it easy to use and a must-have for most professionals.