An MLU is simply a transmitter. In order to be of any use the sheriff/SAR has to be notified to activate receivers/direction finding equipment. (calling 911 will do)

A PLB transmits a distress signal to satellites, providing notification that someone is in distress and the location.
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Doug Ritter
Editor
Equipped To SurviveŽ
Chairman & Executive Director
Equipped To Survive Foundation
www.KnifeRights.org
www.DougRitter.com