AD51U is a 5-volt AC adapter designed to power and recharge Samson AirLine Micro components. It provides a dedicated charging supply for the AR2 receiver and AH2 earset transmitter within the AirLine Micro wireless system. Classified under Wireless Systems / Wireless Components, the adapter is described only by its 5 V charging capability; no RF transmitter/receiver functions, input mains voltage, current ratings, or connector details are published in the available documentation.