A Mountain Locator Unit or MLU is a radio transmitter designed to be used by mountain climbers as an emergency locator beacon when the wearer needs rescue. Unique to Mount Hood, these devices can be rented for $5 at Portland-area outdoor shops and the Mount Hood Inn at Government Camp, which is open 24 hours a day. The MLUs are simple radio beacons, and thus require search and rescuers to use traditional radio direction finding (RDF) equipment that provides a bearing, but not a precise location, to the beacon.