Wireless instruction system. The transmission distance is more than 280 meters in open field without interference. This instruction set consists of: – A blue WHIS transmitter and receiver. – A 220 v duo charger. with which both WHIS devices can be charged at the same time. – A small and discreet clip-on microphone with integrated noise cancellation. – An in-ear headset, easy and hygienic to apply behind the pinna and suitable for each ear. – A spare earphone.