Disclosed is a system of displacing a plurality of parts to be stocked and distributed, each part defining a first end and a second end. The system comprises a conduit, the conduit defining an interior to house an actuation fluid, an axis of displacement in the interior, and an interior surface; and a plurality of devices. Each device includes a periphery configured to contact the interior surface of the conduit and to move along the interior surface, a device first surface approximately perpendicular to the axis of displacement, the device first surface being subject to a pressure of the actuation fluid thereby subjecting the device to displacement in the conduit, a first device-end shaped to receive the first end of a corresponding first part in the plurality of parts, and a second device-end shaped to receive the second end of a corresponding second part in the plurality of parts. The second device-end defines a recess including a bottom surface intersected by the axis of displacement, the recess being configured to center the corresponding second part in the conduit. The device is positioned between the corresponding first part and the corresponding second part in the conduit.