Draper-Expert-600mm-Plumb-Site-Dual-View-39-I-39-Beam-Girder-Section-Level-Draper-Expert-41213-B-I-Expert-Quality-I-B-with-front-viewing-Plumb-Site-174-Dual-View-153-vial-&-I-beam-vial-Manufactured-from-hardened-aluminium-electrostatically-powder-coated-&-baked-with-polyester-acrylic-paint-milled-top-&-base-&-rubber-end-caps-One-horizontal-&-two-vertical-vials-one-of-which-has-a-front-viewing-Plumb-Site-174-Dual-View-153-vial-Accuracy-1mm-per-1M-0-001-17