Shown below is a photograph of the X-ray filters available on a standard Siemens X-ray tube housing. The beam passes through the top filter which in this case is a nickel foil. Alternative metal foils can be set by rotation of the filter housing to the appropriate position. One position on the filter housing is left open for the case when a filter is not required.

The top of the X-ray tube is visible above the tube housing. A cover plate with beam stop (not shown) is then fitted over the filter housing during normal use.