Sentinel multipoint sliding door lock with receptacles for 3 hooks.
3-point Sliding door lock used by Caradco, Jeldwen, Marvin and others.

Backset: 1-3/4 inch ( 45 mm)
Overall Length: 40-15/16 inch, Radius ends
Hooks: 3 - spaced 16-7/8 inch
Lock Body case: 4-1/8 inch

Related Parts & Handleset Trim:
11860041 - 1, Single Hook
4991663 - 3 Point Strike Bar (.755 offset)
14545 - Narrow plate, 1-1/4 inch wide handle set trim
14552 - Wide plate, 1-11/16 inch wide handle set trim
40215 - Less expensive version of this same lock

Operation of Lock:
This lock uses 3 hooks, the center hook goes into the lock case and pushes the plate back. This allows the thumb turn or key to turn and secure door in locked position.

We recommend that before you close your door to check out the functionality of the lock by inserting a screw driver into the center lock position, pushing the plate back and testing the operation of lock.

Door must be level. The best way to check, is close the door, then open enough you can see daylight between the door panel and jamb. The day light gap should be the same from top to bottom. If not, the rollers need to be adjusted.

IF, installing new handle set and the key turns hard when you tighten the handle set screws.  loosen the screws and try turning again. If it turns easy then the flat tail piece from the key and the thumbturn are hitting. They need a small space between to work properly.