Automatic chains may be installed. Sanders, when required or used, shall: Be of the hopper cartridge valve type; Have a metal hopper with all interior surfaces treated to prevent condensation of moisture; Be of at least 100-pound (grit) capacity and refillable from the exterior of the vehicle only; Have a cover on the filler opening of the hopper, which screws into place, sealing the unit air tight; Have discharge tubes extending to the front of each rear wheel under the fender; Have nonclogging discharge tubes which shall have slush-proof, nonfreezing nozzles; Be operated by an electric switch with a telltale light mounted on the instrument panel; Be exclusively driver controlled; and Have a gauge to indicate that the hoppers need refilling when they are 1/4 full.