Wow very loud.

Bought it for scuba diving and while I didn't try it under water, above water it is the loudest whistle I've tried. And the price was great.

I went outside my house to test this out and it was so loud that I blacked out and saw a Mongolian Warrior on horseback galloping to my defense with a huge eagle on his arm.

I came to after my neighbor "Chunk" splashed part of his beer in my face and pulled me up from off the ground.

He then assured me that the hallucination was probably a reflex caused by my unexpected reaction to the handgun-like report this whistle gives off when you blow it hard.

It is unbelievably, almost supernaturally loud.

He then asked me to help him retrieve his dog, who in a state of complete terror had climbed straight up his pecan tree.

No Mongolian eagles were harmed in the process of pulling the dog down.

They would, however, have been most appreciated and helpful as the dog adamantly refused to come down of his own accord.

Five stars.

Edited: My neighbor Charles read my review and was upset that I did not use his nickname, "Chuck," which he is somehow convinced has a more "manly" ring to it.

I have since replaced the name "Charles" with "Chuck."

This whistle is so loud that it is difficult to see what it sounds like without alarming people a block away. I was at a business visiting a friend, who wondered what I had around my neck on a lanyard. I explained. He said he was interested in getting one for each of his employees if it truly was as I had told him. So, we went out back---this is in a small business/light industrial area near an international airport---and sounded the whistle. I had not heard it before. It was so loud that is alarmed me and took my friend's breath away. People came running out of doors 200 and 300 yards away. We could do nothing but look around as if we, too, were surprised. My friend immediately went on-line and ordered whistles.

The advertising says that this produces 120 dB of sound. When robustly blown, it is at least that loud, probably more---which I can say with confidence, having worked in situations where loud sounds had to be measured and evaluated. It is ear-splitting and just the right frequency to shriek and penetrate. The advantage of this whistle is that in most situations, it would be as effective as Mace, wasp spray, or other substances people typically carry for self-defense---even more so, because it would drive off all but the most determined thug without having to risk converting him into a homicidal maniac by a poorly aimed Mace blast. And, yes, a gun is more definitive in its action, but a terminal outcome, while perhaps justified, might have its own distressing consequences.

This whistle is also a wonderful item to have in certain situations where attracting attention for reasons other than personal safety might be urgently needed. Breaking a leg in a rear parking lot where no one is around, for example, might be a real problem unless you could blow that whistle and have a crowd around you in seconds. Or, hiking with the family and getting lost would have perhaps a happier and more timely ending if whoever was lost could blow that whistle.

Get one, or get several for family members, but don't test it without going to an unpopulated area, unless, of course, you are prepared to pretend that you also are surprised and alarmed at the impossibly loud and discordant sound when people come rushing out to see what happened.

The whistle came in simple packaging (plastic bag). You receive just the whistle. No lanyard included which was fine and expected. The size is large (see photo, quarter for comparison) but not so big it can't be carried easily. Have taken outside and tested. It is extremely loud. Plug your ears if you blow hard. I made that mistake and mine are still ringing 30 mins later. Very happy with the purchase.