KASON 18300 Pressure Relief Port, 3-1/2" Diameter, 115V Heated 

Spring Assisted Hinge, Flush Mount - Kason 1248 Series

OEM Quality Walk-In Door Hinge 

OEM Part #: 11248000004

Commonly Fits Model #'s: TK3476

RHS Part #: 40-375

Other Notes: 

Spring mechanism adds extra closing force to overcome air resistance on heavy walk-in doors.  Special high-lift cam system outperforms similar spring hinges.  Cam-rise action reduces gasket wear, even with irregular floors.  Built-in dwell holds door open beyond approximately 135 degrees.  Simple manual operation reverses hinges for use on right- or left-opening door.