The JetScream is a survival whistle from Ultimate Survival, a company that has created and designed several interesting survival products.The Jetscream is big (2.3 inches long) and flat, it has two holes to thread a cord thru like the picture shows so, it is a very good whistle for neck carry, but it is probably a little big for a keychain. It can also be carried from a backpack, a shoulder strap or just in your pocket. As a zipper pull it is too big. Remember the whole idea of carrying a whistle is to have it available in an emergency situation so neck carry is probably the best approach.
In order to produce the sound you don't need to use a lot of force, the harder you blow the louder it will sound so while it can certainly be used by small children it will not sound as loud as what an adult can do. The sound is quite acute and piercing, the frequency when tested resulted particularly good in windy situations and it was also good enough to be noticeable in an urban noisy scenario.
The JetScream doesn't have a pea so it will work without a problem if wet and the plastic material won't be a problem if the weather is very cold. The construction is very strong, we don't think the whistle can be damaged by hits or scratches and pressure will not crush it due to the flat design. It is a real solid whistle.
In conclusion the Jetscream is a loud whistle, bigger than other whistles we have tested but the flat design makes it useful. The sound is very good and met our expectations.
You can read more from UltimateSurvival or order for $5 from EDC depot.