A. EPIRBs and PLBs are similar in that both can alert and summon first-responder assistance when a serious emergency (eminent threat to life or vessel) occurs. EPIRBs should be mounted where they can be quickly grabbed. Some are designed to deploy automatically when a vessel sinks. They have a 48-hour operation time, float upright and have a built-in strobe light to guide rescuers in poor visibility when they approach your location. PLBs are intended for personal use and to be held in the hand, worn on a life jacket or article of clothing, or carried in a pocket. Operating time is limited to 24 hours, not all models float, and PLBs must be held upright with the antenna in a vertical position. Most lack a strobe light. PLBs can also be used on land in remote locations for hiking, camping, mountain climbing, exploring and other outdoor activities to summon emergency help if needed. EPIRB and PLB signals are both broadcast on 406 MHz and both received by the closest RCC (Rescue Coordination Center), which makes the call to the appropriate rescue agency, be it Air Force, Coast Guard, Fish and Wildlife, National Park Service or Sheriff's Office. EPIRBs and PLBs save lives. Don't leave port without one.