Abstract: An apparatus for the interior coating of cavities, particularly of an automobile body, comprising a spray gun having a nozzle probe plug-in coupling and spray shot trigger means and comprising nozzle probes connected to the spray gun, each thereof being allocated to a defined cavity and being composed of a nozzle tube having a plug-in end, nozzle end and positioning detent is created wherein a spray shot is only output or, respectively, can only be output when a full seating of the positioning detent against the outside wall of the cavity has been achieved. This is achieved in the positioning detent is provided with at least one contact sensor that is in an interactive connection with the spray shot trigger means of the spray gun.