Compared with traditional whistle,Electronic whistle can avoid mouth contact. Just press the sound button then it will bring a loud and clear sound. which saves effort and prevents spatter of saliva between users. Whistle with lanyard perfect for referee coaches, P.E. teacher, marine, outdoor camping, sports competitions, traffic guides, pet training, self Defense Emergency. electronic whistle have 3 different tones to meet different needs, All the tone are high volume, can provide up to 120-150 dB sound power. Our mouth-free whistle is made of high quality ABS material, very sturdy and durable. It also has no any release of harmful substances. Easy to get attention and USB direct charging and thus much convenient environmental and save the cost. The electronic whistle with USB charging,It is 10 times more durable than ordinary button batteries., can keep sounding for 4 hours and save the cost of buying batteries. It also has led lighting function,which can assist in lighting in dark environments. Easy to use. It has a comfortable ergonomic design with one-handed operation, and a detachable lanyard for convenience. [Easy to Carry]Hand whistle equipped with a long lanyard, it can easily loop through backpack, sailboats, camping hiking gear, life jacket, kayak . You can also tie the whistle to your neck, shoulder straps, belt and backpack or put it on the pocket for quick and easy use in case of emergency. Colour:Black Material:plastic Package Contents: 3 x Electronic Whistle 3 x usb cable(Color and style are random, don't accept the specified) 3 x Lanyard(Color and style are random, don't accept the specified)