A gas detector can be releasibly coupled to one of a group of elongated probes each of the probes includes a detector connecting end and a gas in flow/outflow end. The connecting end includes a helical attaching feature which when coupled to the detector defies a plurality of spaced apart angular locking positions. A locking position is selected in response to a flow of air in an adjacent duct to which the detector is being attached. Where the detector carries an elongated display device, the locking position can be selected so that the display device exhibits a desired presentation.