Face plate only for 2 point mortise lock; Long Trim plate
This is one of several sizes and shapes used with the 15183 mortise lock with 2 hooks

Commonly used with the newer wood and vinyl sliding patio doors

Width: 3/4 Inch
Length: 11-3/4 Inches
Material: Stainless Steel

Note:
The 15183 mortise lock has several face plates that are used depending on application, some flat, others are raised.
Basic screw hole spacing for the plate to lock mounting is 4 inch
the offset holes are for the anti-slam pin.

Related 2-point Mortise lock parts:
15183 - Lock Body Only, 2-point without face plate
15194 - Trimplate: 9/16 x 9-3/8