Cat. No. Used-AFi-metal-cover-mb
Used: Leaf AFi sensor cover plate (may also fit Credo)
I'm not sure why I have two extra of these plates, but I do. If you misplaced yours, I've got you covered.
This is the metal locking plate that protects the sensor on the AFi and AFi-ii digital backs when its not on the camera (when you're experimenting with film).