The Sabre Sport & Safety Horn is promoted for use at sporting events, personal safety, boating, and camping/hiking. Essentially it is a small air horn with a blast of 112 dB. While there are many different air horns, along with various sizes, the convenience of this horn by Sabre is that it is very small and easy to take with you or have tucked away. However, this means you won't have a lot of blasts with it either.
Many sporting events don't allow these, so I would not recommend taking them to events where it could get you in trouble. As for boating, camping, hiking or personal defense, there is some use for having a small air horn with you.
When it comes to personal safety, having a whistle, air horn, or other personal alarm can be a layer in one's safety measures, but should not be relied on to be the only thing. They might distract an attacker for a second or two allowing you to escape, or they may alert others to your distress and get someone to come help you. But don't count on it. Many people are inured to the many false alarms that constantly sound and just ignore them. In secluded areas, an alarm would not be much help with no one to hear. And there is always the danger that an alarm might enrage your attacker. So while they can be one measure in your overall personal security plan, you must have more than just this, and be prepared to act if the noise fails to achieve the desired effect.
As something to scare animals away while camping or hiking, this can be good. It can also notify people at a distance. So there are uses. I actually use larger cans during our Active Shooter Response trainings to stop the scenarios we run.
Bottom line: This Sabre Sport & Safety Horn isn't a bad thing to have in your kit or to carry, but just be aware of its limitations and don't rely on it to be your only security device or option.
The Sabre Sport & Safety Horn is available at amazon: