There is provided a cassette unit that is suitable for use with an auto-injector having an electrically powered drive unit. The cassette unit has a housing defining a cassette unit housing cavity and a needle projection aperture. The cassette unit housing cavity is arranged for receipt of a syringe that is suitable for use in the injected delivery of drug to a patient. The cassette unit includes a removable cap that fits over and thereby, acts such as to close off, the needle projection aperture; and connecting to the removable cap, a needle cover defining a needle sheath for sheathing of the needle tip of the syringe. The removable cap is provided with a finger-grip feature that is sized and shaped for gripping by the finger of a user to allow for removal of the removable cap and needle cover from the cassette unit housing.