Brusso ST-18 Knife Hinges
The ST-18 brass center pivot hinge is employed when a minimum of visible hardware is desired or when the door must swing free of its frame. It is mortised into the top and bottom of the door and frame; only the pivot is visible. The leaf measures 1-3/4" x 3/8" x 1/8". The hinge is sold in pairs and installation instructions are available.