The hollow shaft version of the FGH 40 is utilized to measure speed in heavy industry applications such as in steel and rolling mills, in the mining industry as well as in ports and crane systems. Rated to protection class IP65 / IP66 the device is extremely robust, the hollow shaft is made of corrosion-resistant stainless steel, the casing is made of aluminium. The hollow shaft is available in diameters between 16 and 20 millimeters.