An identification device includes an ultrasound transmitter unit and an outer housing which receives said transmitter unit, said outer housing including one or more apertures which are sealed by a membrane, said membrane being substantially transparent to ultrasound when compared to the rest of the housing. Thus, the face mask is mounted on and removed from the helmet body easily and rapidly by operation of the binding device, so that the crash helmet is assembled and disassembled easily and rapidly, thereby facilitating a user mounting and dismantling the crash helmet. The compositions comprise from 200 to less than 400 ppm oxygen; from 200 to less than 400 ppm of a second gas selected from nitrous oxide, nitrogen, and combinations thereof; and the remainder being an inert gas preferably selected from argon, helium, and mixtures thereof. In this way, the oxidation life under the contamination of water content is improved.