Patented vial with mirror for clear view when placed on vertical position on the wall Shock proof acrylic block vials calibrated at highest accuracy of 0,5mm/m (0,029°) Made of anodized aluminum with 2mm thickness Rubber side parts for stability against the wall Ergonomic Bi-material grip from sizes 80cm and up Patented Vials with Mirror Rubber Side & End Caps Super Strong Rare Earth Magnets - Base made on a lathe Shock Proof Acrylic Block Vial