The hinges have an allen head on top to allow spring winding with an allen key. The UL Series have a 1 1/2 hour fire rating.
Spring hinges use the energy stored during the opening swing, in the coiled spring, to close the door. For doors to 60 pounds, use one UL and two same size ball bearing hinges. For doors to 110 pounds, use two UL hinges and one same size ball bearing hinge. For doors to 160 pounds, use three UL hinges.