Many divers fit a second demand valve, often called an "octopus", to their diving regulators, for emergency use by another diver. Some go so far as to recognise that the out-of-air diver will want the demand valve they are breathing off at the time, as it is indisputably providing breathing gas, and almost certainly a gas suitable for the current depth. These practice "" in recognition of this tendency, and often use an extra-long hose (up to 7 ft long) to facilitate the procedure in tight spaces. These divers often wear the secondary demand valve on a "" which keeps it ready for immediate use under the diver's chin, where it can be retrieved for use without the use of the hands.