Abstract: A device for fitting to a user's mandible such that the mandible is held in an advanced position. The device comprises: an elongate member comprising a first end portion, a central portion, a second end portion and at least one securement point; and a support member extending from the securement point to, in use, maintain the device in a maintenance position on the user's face; wherein the first end portion is arranged to engage one ramus of the mandible, the second end portion is arranged to engage the other ramus of the mandible, the central portion is arranged to engage a first area of the user's face or head other than the mandible, and the support member is arranged to engage a second area of the user's face or head other than the mandible.