This is the Hollis Scuba Diving Regulator Nacklace Adjustable Features:Fully adjustable Hollis&'; regulator necklace takes a new twist on a tool that technical divers have used for years to keep the back up regulator stowed under the chin. Fully adjustable, the Hollis necklace can be worn by any size diver and adjusted to fall on the chest according to individual diver preference.