High pitch shrill of whistle is over 120 decibels (as loud as a Jackhammer). The semi-spherical pea produces a very distinctive sound. Convenient key chain notch for clip or ring, comes with 1 inch spilt ring. Makes sound with little air pressure. Non-stick pea design. Will not stick to lips in the cold. No rattle, slim profile, and lightweight and extremely durable. This is a very well made, patented piece. World's finest and largest selection of badge holders. 1.65" L x 2.0" W