Commonly refered to as ratcheting top cover, smg top cover, many different name, same part. The charging knob/slide clicks as it (and bolt) are drawn rearward, so if you accidently let go of charge knob before locking bolt back via sear, the works will not slam shut and possibly fire if bolt manages to pick up a round. Must be pulled fully rearward to allow handle to return home.
Ratcheting top cover is a std part to the Uzi SMG. If it does indeed have a semi cover (non-ratchet), replace it now, though that mistake should not go out Vectors front door.