This comes with a loud horn that blares when someone disturbs your locked bike. You set it with a remote control fob. They’re not very attractive and they’re somewhat large, but it’s a trade off I’m willing to make and perhaps you are too. Installation is easy. It charges via USB off a standard phone charger. The documentation says the horn can be sounded 1000 times before it requires a charge.
Order at https://juicedbikes.com