Abstract: A ball hitch assembly consisting of: a center pin mountable on a tow bar and having an axial extent; a hitch ball with a central opening mountable on the center pin; a cooperating locking pin and groove structure provided one on the center pin and the other on the hitch ball, with the groove having an entryway through which the locking pin can pass as the center pin is directed into the hitch ball central opening, with the locking pin being movable within the groove to allow the hitch ball to be placed in an operative position on the center pin; and locking structure defined cooperatively by the locking pin and groove for preventing the hitch ball in its operative position from being disassembled from the center pin by drawing the hitch ball in one axial direction and turning the hitch ball in either direction of rotation about the axis of the center pin.

Abstract: A liquid-filled sealing cuff of an airtight surgical ventilating device is protected from laser-effected damage during laser surgery by a liquid-containing barrier cuff positioned between an area of the laser surgery and the liquid-filled sealing cuff. The body of the surgical ventilating device is formed of a matte-finished flexible metal tube in the area of the laser surgery to resist damage by laser beam impact and to dispose highly unfocused light when a surgical laser beam is directed against the outer surface of the metal tube. A locking ferrule prevents disengagement of an atraumatic insertion tip of the device from the flexible metal tube.