Very cool idea, great price, but I have my doubts about it for several reasons.

I doubt it is nearly as loud as a Fox40 whistle.

The red LED light is not nearly as useful for my family, several have a very hard time seeing the deep red colors, and they even give my mom a headache. In fact, I have found that it takes such a bright red to be able to make out details that it destroys my night vision more than a white light of brightness minimal to use for the same purpose. Green, yellow or white would be much more useful to me overall than a red.

I do not know what batteries it uses or if they are replaceable, nor do I know how durable the item is, but for a buck it would be worth it to try one out.