A system for removing or tranferring a pharmaceutical product from a reservoir including an ampoule with a moveable piston therein and an adaptor which includes, generally along a longitudinal axis, a reservoir connector and an ampoule connector for coupling to the ampoule, wherein the ampoule connector includes at least one locking mechanism which, in a side wall, includes a resilient element generally corresponding to a portion of the side wall which extends along the periphery thereof and, at opposing ends, merges with the side wall.