A kit of parts which is assembled to form downhole apparatus and a method of forming the same are described. The kit of parts comprises a swellable member, which expands upon contact with at least one predetermined fluid, and a connector. The swellable member has a first mating profile towards a first end and a second mating profile towards a second, opposing end. The connector has a mating profile configured to mate with each of the first and second mating profiles of the swellable member. The connector can therefore be connected to either the first and second ends of the swellable member. The connector may be an end connector, or may connect the swellable member to a second swellable member. In either case, the connector may define an arresting surface against which the swellable member abuts when expanding. The kit of parts can be adapted to and installed on any well tubular, and may form any of a variety of tools including a well packer, a centraliser or an anchor.