Signalling/Distress Whistle. British Admiralty, NATO and Safety Of Life At Sea (S.O.L.A.S.) International Regulation approved location and warning device. Loud dual frequency selected to be discernable from general background noise. Low noise attenuation for carrying long distances. No moving parts. Operates at half normal lung pressure to ensure effective use even when suffering from breathing problems, e.g. hypothermia, injury. Functions when wet. Suitable for use on life-jackets. Made from high specification tough shatterproof plastic that will not adhere to skin in sub-zero-temperatures. Individually tested. In use with the Admiralty and British Army since the 1970s. Available in white for safety and rescue purposes and black for military field use. New stock - manufactured in 2015. Made in England.