4 Pack of 4”x4” (5/8” radius corner) Interior or Exterior Door Spring Hinge in Iron Black Finish. UL Approved This spring hinge is recommended for use where automatic self closing door is required. The four knuckle hinge is adjustable and the spring tension can be increased or decreased by using the included adjusting tool. Spring hinges for door are fully assembled and include all necessary screws. As a bonus we gave a free Door Stopper in case you don’t want the door to close all the way at all time.