An open chamber-type X-ray fluorescence analysis apparatus is provided to analyze a large-sized sample located outside the open chamber. The stake section has a pair of monolithically formed shoulders diverging forwardly and away from the spine. Alternatively, message display panels, also responsive to the controller, are applied to one or both of the upper and lower sides of the traffic signal, and additional arrays of LEDs are provided in the positions of two of the traffic lights to emit standard color lights during normal operation and to display graphic directional symbols in response to emergency signals. In an implementation, the stop element includes a stop head and a releasable affixing member.