Lev-o-gage BL2 is an extra-large (10.5" wide) boom angle indicator designed to mount on the LEFT side of the boom. Front hashmarks are engraved and Titanium-white paint filled, for optimum clarity. Borosilicate glass tube assembly is Saturn-yellow with a black, high-contract ball for optimal readability. Fluid-damped for smooth, reliable readings. Won't rust or bind like pendulum-type indicators! Working temperature range of -40° F to +145° F (-40°C to +63° C). Mounts with two screws (not included). Perfect for rough-terrain forklifts, aerial lifts, boom cranes, fire trucks, cranes, and derricks.