A quick learner from Egg Harbor Township, NJ says:
July 13, 2021
This is the piece that the hook on the sliding door lock hooks into. It mounts opposite the lock mechanism on the door framer with 2 screws. This one broke so I cant show it mounted very well. It is 2 3/4 inches long. Thanks
Emily from SWISCO responded:
July 16, 2021
Hello!
This reminds me of our 89-018 keeper. Look over our dimensions and compare them to your original hardware and see how they match up.