BestBuyGoods Special Offer 5pcs Dual-frequency Compact Survival Emergency Whistles With Luminous Lanyard for Camping Backpacking Fishing Running Cycling Boats Raft Marine Wild Living Outdoor Training Survivor Emergency Both of high pitch and low pitch. A great attention getter!Ideal for emergencies Integration design,compact and durable,Whistle mouth with resistance design. Built in clip design, it can clip on bag or clothes 5 pcs For communicate with each other.