The Coghlan's Emergency Survival Horn is very loud! It operates with the simplicity of a mouth horn and blasts out audible sound up to 120dB. The membrane can be easily replaced with any thin flexible film. Comes with SOS printed on the body and a black break away lanyard. Wt. 1.4 oz 39.7 g Sizes: 2 1.25 x 3 5 cm 3.2 cm x 7.6 cm Durable polypropylene Great for coolers, tackle boxes, toolboxes. Batteries included uses three LR44 1.5 volt button cell batteries Features a stone and twig guard to protect the rubber membrane and comes with a break away lanyard.