John, I've wondered about this particular PLB (ACR Aqualink 406 PLB 2882) ever since I started researching EPIRBs and PLBs. And I've wondered ever since, why this is referred to as a PLB and not an EPIRB. The registration appears the same as the EPIRBs, to include the name of the owner, contact info, home port, address, etc, plus the name and type of vessel, and must be re-registered every two years. All these requirements are the same as the EPIRBs. The only difference that I notice is perhaps the quality (tolerances of electronic components, etc), and the size. The battery life is shorter, according to specs, but the output power is the same. Otherwise, I really find no reason they don't call this an EPIRB. Then there are the classifications of EPIRBs, which I'm not familiar with (Class I, ClassII). Perhaps more informed individuals could shed light on this, since all I know is what I've read on ACR's website. But whatever the differences, I don't think I need anything more than this.