The only reason I give 2 stars is for the wasted metal. Stay away!!!
From the first day, it has an issue with unlocking. While turning the key, the bolt does not release. We're talking about strong nerves

Heavy construction. Solid and good design on how the battery is inserted. The siren is moderate to loud. For a padlock alarm (and not for a complete alarm system) it is powerful. The only reason I don't give it 5 stars is because sometimes the siren doesn't arm immediately and you have to unlock and relock the padlock (rarely), but it can be done. The good thing though is that when you lock it, it makes a small beep and after 3 to 5 seconds if the siren is armed, it makes a louder second beep. So there is no chance for anyone to get confused and not realize that the alarm is not activated. Honest.