Abstract: According to one embodiment a necking machine is provided for containers with an open end. The necking machine may comprise a plurality of holding stations for containers and a plurality of tool stations contiguous and opposing the holding station. The tool stations being movable with respect to each other. The machine also includes an inspection device for containers that includes a light detector for detecting light in the interior of each container. The inspection device is attached to a tool station such that the inspection device shifts together with the tool station with respect to the container during the inspection of the container. Light communication of the light detector with the interior of the container being maintained during the inspection.

Abstract: An apparatus for measuring the inner volume of a cavity. According to one embodiment the apparatus comprises a hollow body coupleable to the cavity, such that the inner volume of the cavity and the inner volume of the hollow body are communicated. A solid body is housed in the hollow body. A detector monitors the position of the solid body. A processor determines the inner volume of the cavity which is calculated from the oscillation of the solid body according to the volume of gas inside the cavity.