Tool has a casing over the pneumatic mechanism, a handle projecting from it, and a control valve through which the air supply and outlet systems pass; the control system has a valve for the air supply, a rod which is pressed from the handle, and an arm which is hinged on the handle so that the air supply is opened if the rod is depressed. The handle contains one part which is made one-piece with the casing by casting in a resin material; it contains also a valve housing which is also cast in resin; the one part mentioned fits tightly and seals the housing which itself contains the valve and rod; both the air supply and discharge systems are in the valve housing. A pref. polymer for the resin concerned is polycarbonate.
