STABILA, INC. 37424 - LEVEL BOX 24IN TYPE 196 ALUM - 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. - EQUAL TO 7830649