Editing Scuba set (section)

===Mouthpiece retaining straps===
<!-- target for redirect [[Regulator necklace]], [[Mouthpiece retaining strap]] -->
A [[mouthpiece retaining strap]] (MRS) is an item of safety equipment which is a mandatory design feature for rebreathers sold in the EU and UK, following European rebreather standard EN14143:2013. Mouthpiece retaining straps have been shown in navy experience over several years to be effective at protecting the airway in an unconscious rebreather diver as an alternative to a full-face mask. The arrangement is required to be adjustable or self adjusting, to hold the mouthpiece firmly and comfortably in the user's mouth, and to maintain a seal. The MRS also reduces stress on the jaw during the dive.<ref name="RTC MRS" />

Mouthpiece retaining straps have also been used with open circuit scuba, both on single hose and twin hose units. They were quite common as original manufacturer's equipment in the 1960s, when they were usually called neck straps,<ref name="Basic Scuba" /> but at some stage lost popularity. The technical diving community later developed a similar functioning accessory generally referred to as a {{visible anchor|reguator necklace}} or bungee necklace, an aftermarket or home made elastic loop, generally used to hold the secondary demand valve in a position under the chin where it can be accessed hands-free by tilting the head.<ref name="Jablonski 2006" /> It can also be used to hold a primary demand valve in the same way, which will keep it in close proximity to the face if accidentally dropped or dislodged, making it often possible to recover hands-free. This type of retainer does not necessarily keep the mouthpiece in place in the diver's mouth or maintain a seal if the diver loses consciousness, as the fit is not always adjustable. The bungee necklace can be pulled away from the neck with a moderate force, causing the rubber mouthpiece to pop out of the retaining loop.<ref name="Davis b" />