Alloy Metal Shell Bullseye Level for Engineers , &Oslash;74mm ,Accuracy 15'/2 Stable over a wide temperature range and highly resistant to shock Applications:Precision Instrument Levelling .High precision weighing scales. Sensitivity 30' per 2mm bubble movemement Optimum vial quality and bubble size gives fast settling They are typically used on equipment, vehicles, cranes and lifts,Excavators and dumpers