Pneumatic vices are used for clamping workpieces on production machines such as machining centres, transfer machines, drills and for the assembly of various parts. The workpiece is clamped by means of an interchangeable gripper housed inside the device; the advantage over other clamping systems is the perfect centring of the workpiece. They are designed with a double-acting pneumatic system; both closing and opening of the gripper are pneumatic without the use of springs to return the sleeve. The external body of the device is designed to be fixed on the machine tool in both horizontal and vertical positions.