Hager 4" x 4" x 5/8" Full Mortise Spring Door Hinge. Use these hinges on exterior doors when you want the door to automatically close once opened. The speed of the close can be adjusted using a common allen wrench which is included in the box. For best results, use two spring hinges per door. Material: - Steel Finishes: - USP, 1D, 2D, US3, 3LB, US4, ABA/US5, US10A, US10R, US15, AN/US15A, US26, US26D Packaging:- 2 pack with screws Notes:- For maximum versatility use all spring hinges or a combination of spring hinges and ball bearing hinges. Do not use plain bearing hinges. - Full spring tension may not be required on all hinges - Strong wind conditions, drafts, carpeting drag, twisted/misaligned frames, or weatherstripping on doors may require additional spring hinges.