Black Storm All Weather Worlds Loudest Whistle (10358) Loudest Whistle On The Marker Can Be Heard Through Walls, Through Glass & Through Water Can Be Heard Over A 0.25 Of A Mile Through Trees & over 0.5 Miles Over Water Decibel Reading Varies Between 118 & 120 DBs Unique Patented Design Allows It To Be Heard Under Water, Up To 50 Feet The Sounding Chamber Forces All Water To Be Purged When The Whistle is Blown Creates A Clear, High Frequency Sound, With A Power Rating Over 75% Greater Than Other Whistles Navy Seals & Coast Guard Approved Used By The U.S Military, Police, Fire Fighters, Campers & More GSA Compliant Made To Withstand Rugged Use Made In U.S.A