to respond negatively and for this purpose the checked person has first to remove small metal objects such as keys watch mobile phone or the like and put them on conveyer 333 through opening 332 after removing such metal objects the person may pass the metal detector 322 and the door 335 can then be opened when the door is opened the small objects being conveyed by the conveyer 333 from the opening 332 are protected from above by a transparent plate the content of the small objects is thus visible to a guard in the guard tower 271 either directly or through a camera and monitor system or the guard tower 270 and in case a suspected object is identified e g a small pistol a knife etc the guard may halt the conveyer before the object reaches the outlet opening 334 of the conveyer 333 in the case that the conveyor is halted by a guard the person is captured between the doors 335 and 336 until reached by guards for further treatment under normal conditions the door 336 can be opened and the person can pass through and enter the protected region only after removing his small objects from the conveyer through the outlet opening 334 this can be recognized automatically e g by a load cell that weighs the load on the conveyer or e g by photocells which detect interruptions in a light beam scanning the conveyer this ensures that such objects will not be forgotten by their owners another final.