A full function electronic flag set at a great price. Set includes two flags for the assistant referees, an arm receiver for the referee in the middle and a distinctive set of OSI checkered flags plus flat flag case. Most OSI swivel flags will fit on these poles. The receiver can be set for sound only, vibration only or for both sound and vibration. The system has been produced for all kinds of weather and will perform very well in wet conditions. Easy to use and each component takes a standard 9V battery. A set of three batteries is included with each set. Exclusively from Official Sports. 1 year warranty.