Powerful GripTight™ v-groove rare earth magnets hold to flat or round ferrous metal surfaces, Lifetime guarantee, Guaranteed accuracy, Patented Glo-View® recharges the vial surrounds from light sources for easy-read in low light, Domed level vial offers 320° visibility, Large comfortable rubberized hand grips, Reinforced aerospace aluminum allow frame, Removable GripTight™ end caps hold level in place.