For Residential Single And Multi-Family Hall/Closet Doors. Both Knobs Always Unlocked. 1 Piece Knob. Solid Brass Trim And All Metal Parts. 3 Piece Assembly. DUAL OPTION UNIVERSAL: Fits All Doors; 2-3/4" Or 2-3/8" Backset; 1-1/8" Square Corner, 1/4" Round Corner, Or Circular Drive-In Preps.