Mortise Lever Lock used on Larson Lifecore Series storm door
 
Special 4-3/4 inch screw hole spacing.
Inside thumb button to lock handles. ( No Deadbolt, No Key ) 

Dimensions of Latch Face Plate: 5/8 x 2-5/8
Backset: 1-3/16 inch ( edge of latch to center of handle hole)
Fits doors from 3/4 to 1 inch Thick. 
Projection: 2-5/8"

Used on several Larson storm door Models. 274-FL Fullview, 287-CF, 271-TT, 275-SS & 278-SS Self Storing