This 3-1/2" Satin Nickel Finish Spring Hinge is designed for hanging self-closing doors in basements, stairways, garages, & entrances, etc. Can be used in residential, commercial, & apartment buildings. Hinge is UL approved for fire doors. Closing speed is adjustable. Fits standard hinge cutout. 1/4" radius, round corner automatic door-closing spring hinge. Satin Nickel Finish on cold-rolled steel material. Sold as a single hinge in pack.  National Hardware Model No. N350-835.