ADS 0601DI 6" Nyloplast Round Light Duty Drop-In Grate. Nyloplast offers a wide variety of ductile iron castings from light duty drop in grates to heavy duty 2 ft. x 3 ft. curb inlets as well as decorative bronze grate options. These castings easily connect to our basins and piping systems. Our vast assortment of grates and covers are tested to ensure they meet specific load and inlet capacity requirements for any application whether it's for use in a green space or traffic application.