The present invention concerns a device for fastening an emitter to a housing comprising a first, manoeuvre element being slidable in a first direction, a second, activating element being slidable in a second, fastening direction being inclined in relation to said first direction, whereby the first and second elements are interconnected via at least one cam mechanism. In one example embodiment, a containment berm bracket includes a substantially rigid first member and a substantially rigid second member. The cover portion can be permanently attached to the sleeping means but further edges of the same can be selectively attached using zips or other fastening means. A cap member is supported on the valve body and includes an interior surface and an exterior surface and is positioned over the second valve end for movement in a longitudinal direction parallel to the longitudinal axis. These changes specify one or more desired phenotypic changes in the resulting virus or subviral particle.