1Interior Door Mortise 2.5 Backset IML-005May 28, 2022/in Interior Door Mortise Lock Hardware/by adminInterior door mortise for 1/4″ spindle with 2-1/2″ back set most of these smaller mortises typically have a 2-5/8″ back set. Face plate measures on two of them 7/8″ x 3″. 2 MATCHING MORTISES AVAILABLE