Shoemaker 945-12X4 12"x4" 4-Way Adjustable Diffuser - White 945 O - Steel Lever Operated Opposed Blade Damper 945 O Steel Lever Action Opposed Blade Damper Adjustable Steel Blades With Steel Multi-Shutter Damper All Component Parts, Rivets, Linkage And Handle Enclosed In Valve To Assure Easy Operation