A system with a container including a protrusion, and a receiver to receive the container. The receiver includes a slide block that is movable relative to a body of the receiver, the slide block including two surfaces, a first surface, initially contacted by the protrusion of the container during insertion of the container into the receiver, having a first slope to resist movement of the container towards the receiver, and a second surface, subsequently contacted by the protrusion of the container during the insertion of the container into the receiver, having a second slope to interact with the protrusion of the container to assist movement of the container towards the receiver. This construction provides the user with a changing insertion force to indicate proper mounting of the container.