Magnetic edge holds to ferrous metal surfaces. High impact structo-cast frame is non-conductive and non-corrosive, v-groove edge fits on pipe and conduit. High visibility. High impact frame is non-conductive and non-corrosive with V-groove edge fits on pipe and conduit. Magnetic edge holds to ferrous metal surfaces (model 7500M). High visibility on job site (models 7500-ORANGE and 7500B-ORANGE).