The elite forces operative was on an admin run but ran back to his car to collect his equipment. Emergency provision of an alternative breathing gas source is required in case of a failure of the primary gas supply. This allows communications equipment usually an intercom wire or by modulated ultrasound to be installed in the mask and is very useful for working divers. This mask has a clip-on pod section which carries the demand valve, and this part seals against the lower part of the frame, allowing the diver to remove the regulator pod when on the surface, or to use an alternative gas supply, which can either be mounted on another pod, or be an ordinary Scuba regulator second stage with a standard mouthpiece. Kirby-Morgan makes a unique configuration of full-face mask, the KM Supermask, which has some characteristics of a half mask, while retaining many of the advantages of the full face mask: A hapless St Bernard dog was left with a face full of painful quills after trying to befriend a porcupine.
The procedure lasted 25 hours and ended the following morning.
Full face diving mask