Devices for measuring a nip width between rolls of a press nip include one or more sensors adapted to be placed in the nip while the nip is stationary. Therefore, when an impact force from front or back equal to or more than that prescribed is applied, the flat spring member increases in tension by backward moment applied to the seat back, and serves as a function to increase again the intensity of the backward moment of the seat back, which was once lowered by deformation of the side frame of the cushion frame. The RFID circuit preferably is carried by a stop flange that extends from the tamper band, and is disposed between the stop flange and the tamper band. The infiltrant layer is formed from a metal powder, that is of a lower melting point, admixed with a second binder. Consequently once such detection is made and the air is verified as being safe, the contents can be removed safely. Application to the coding of a digital signal representing an image.