There are various ways of lifting irregularly shaped items. While the most common lifting devices in robotic arms are flat surface grippers, these types of devices are most efficient with flat surface workpieces and are not nearly as efficient with round, cylindrical or other irregularly shaped items. When used inappropriately, flat surface grippers can either crush the workpiece or drop a workpiece due to inefficient grip, especially in high-speed operations. A pneumatic mandrel lifting device is used to lift objects that are hollow. The gripping action of a mandrel lift is applied to the interior of the workpiece. Low pressure air is channeled to a chamber behind a diaphragm. The diaphragm then expands until it is firmly gripping the interior of the workpiece. To free the workpiece, the air is released from the diaphragm which then deflates, allowing the robot to relinquish the item. Numatic pen lifting devices work similarly to mandrel lifting devices. The main difference is the location of the gripping action of the tool. With a pen lifting device, the gripping action occurs on the outside of the part. As the tool surrounds the workpiece, low pressure compressed air is used to expand the diaphragm. This ensures a snug grip on the exterior of the workpiece. To free the workpiece, the pressurized air is released, which deflates the diaphragm and allows the workpiece to drop freely. The single disadvantage of these pneumatic lifting devices are the limits on the payload or weight which they can lift. However, these flexible pneumatic devices have many advantages, including their lightweight, their ability to grip parts without damaging surfaces, and their ability to grip parts with irregular shapes.