Abstract: A manipulator for handling objects within a sealed environment, such as an ultra-high vacuum chamber, is mounted on a port of the chamber so that an active portion of the manipulator terminating in a set of gripping jaws is located within the chamber, while an operating portion of the manipulator is located externally of the chamber. The gripping jaws are mounted at one extremity of a shaft for rotation through at least 360.degree. irrespective of whether they are in an open or closed configuration. The jaws are opened and closed from the exterior of the chamber by means of a sleeve which is axially slidable on the shaft by means of a drive ring located on the operating portion of the manipulator.