STABILA 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 ideal 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.Every level is electronically adjusted, then accuracy inspected and certifiedVials read the same in all positionsBright easy to read vials will not leak, break, fog or require re-calibrationLevel accuracy assured for lifeRib-reinforced frame for high-strength and lightweightFrame will not warp or twistRubberized hand grips for comfort and gripShock-absorbing end caps prevent slipping on walls and are removable to carry lines tight into cornersEndcaps can be removed to carry pencil lines tight into corners