An inner elongated tubular member, a plurality of arms which extend through openings in the elongated tubular member and a concentric outer sleeve moveable relative to the inner tubular member for urging each of the arms into engagement with the hub of a needle attached to one end of a cartridge to lock...http://www.google.es/patents/US5002537?utm_source=gb-gplus-sharePatente US5002537 - Hypodermic syringe
