SOSS now offers a complete line of fire-rated invisible hinges. Whatever the door or opening, there is a SOSS hinge for you. Whether your doorway is made of wood or metal it is rated 20 minutes or 3 hours. It will comply and still give you the "uniquely invisible" hinge that you expect from Soss
Features
90/180 Min UL Fire Rating, 1 each
Additionally, they can be used on wood core doors
Specifically designed with square edges for metal doors
Use at least one fire-rated hinge for every 20" of door height
Used on hollow metal, sheet metal, tin clad and steel composite swinging type fire doors
Not to be used on a door that normally is held open