Featherweight, and loud as a banshee. I was banned from using this at my previous security job because attempting to get someone's attention who jumped the security fence and bypassed the checkpoint, my supervisor heard this across the facility a couple hundred feet away through hundreds of people's background ambience noise and the facility's radio music clear as a...well, as a whistle. Lol. If that doesn't tell you it works, nothing will. This could potentially be used as a sonic attack at close range, and has excellent use as a survival device. It takes little effort to make it pipe up. I advise quick, hard breathing taps. Tends to hurt your ears less than laying on it fully.