A closable opening device having a frame defining a through hole and fitted about a pierceable portion of a sealed package for pourable food products; a removable threaded cap which screws onto the frame to close the hole; and a tubular cutting member screwed inside the hole and rotated by the cap to travel through the pierceable portion. The apparatus includes a first cable alignment rod that is attachable to an upper portion of the bow for deflecting a first section of the cables extending between an upper cam and a cable guard. This enables the disabled user to carry this keyboard from one computer system to another and simply exchange it for the standard keyboard for the computer. The injection lumen can alternatively or additionally include at least one flow-modifying protrusion extending from the inner tubular wall of the injection lumen and toward a longitudinal axis of the injection lumen. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods for producing and using the polypeptides.