Cal Royal Steel Full Mortise Hinge - Satin Chrome BB31-26D

4.5 x 4.5 Full Mortise Hinge, Square Corner, 5 knuckle, .134 Gauge Steel, Ball Bearing for Standard Weight Doors, Removable Pin, Satin Chrome Finish

Classroom Lock Function: Lock operated by lever from either side except when outside lever is locked from outside by key. When outside lever is locked, latch bolt is operated by turning inside lever.