Tough aluminum frame with two patented strikes zones to protect from the repeated hits of a trowel Reinforcing ribs on the frame for added strength and grip Precision-milled measuring surface Always at eye level – the second plumb vial is offset towards the center, making it easy to read in all measuring positions Shock-absorbing, removable end caps – protects the frame against repeated drops and falls Easy to clean with water and brush The white housing material around the vials is contoured so it is easy to clean