This document covers the basic design principles for building Auracast^™️ earbuds and other receiver devices, explaining their features, their configuration requirements, and how they interact with other Auracast^™️ devices. These principles also apply to speakers, hearing aids, headphones, and soundbars. The focus on earbuds illustrates the additional design issues encountered when two independent Auracast^™️ receivers need to synchronize to the same Auracast^™️ transmitter.