Digi-Bee 17-channels, 863-865MHz is the noise-free guide system that minimizes the unpleasant noise caused by internal and external interference. The easy to use transmitters and receivers with smart channel synchronization, weighs only 70 grams including the battery. That, combined with the pure sound makes the system an excellent choice for guided tours. The system is also designed to be combined with a neck loop to work for hearing aid users and thus satisfies the requirement of availability for the hearing impaired. Full charge provides up to 15 hours of use and the range is approximately 50m. You can temporarily replace the rechargeable batteries with standard batteries. With different colours on the units you can easily keep them apart the receivers are black and the transmitters are white. A blue led light indicates when they are paired.