For residential single and multi-family bed/bathroom doors. Pushbutton locking, opens from outside with small tool; turning inside knob releases pushbutton. 1 piece knob for increased security. Solid brass trim and all metal parts. 3 piece assembly. DUALOPTION UNIVERSAL: Fits all doors; 2-3/4 in or 2-3/8 in backset; 1-1/8 in square corner, 1/4 in round corner, or circular drive-in preps.