Review on Xflyee Electronic Whistle: USB Charged With Adjustable Tones, Perfect For Referees, Coaches, And Outdoor Safety by Jason Holt

I use this unit to ref convention ctr volleyball tournaments. This means 8-9 best of 3 matches each day. Every rally starts and ends with a whistle. That is a lot of whistles and yet I can get thru a whole day on one charge. Also, in this setting there are whistles going off on courts all around me but the players on my court are able to hear my signals. Lastly, I had one venue where the courts were so close together I could literally shakes hands with the official behind me. I was able to select a different tone from that ref so the players were able to tell which one of us was giving the signal .