Electro-Voice RE3-BPTRSB - Referee Switch Bodypack Wireless Transmitter (5H Band / 560 - 596 MHz)Wired to work exclusively with the RSB 2 Referee Switch, the RE3 BPTRSB is a small, lightweight yet robust UHF bodypack transmitter. It is easily worn and concealed, making it the ideal form factor for the rigorous use expected during sporting event officiating. The all metal body is robust and durable, and operates on 2 AA alkaline or rechargeable NiMH cells. The ultrasonic sync function makes for a simple system setup by syncing the transmitter to