STABILA STA-37448 - 48" Level with Hand HoldsSTABILA levels are unparalleled with regard to their accuracy and dependability. The secret the vials made of block acrylic glass are firmly epoxy locked in the frame. A perfect system. The vial is firmly cast in the high strength aluminum frame with non shrink epoxy. No re adjustment, no realignment, no tensioning against springs made of steel or fatigued plastic, no welding or clamping stresses. Just as accurate after 10 years as on the first day.