First off, let me say these Sanjie Door Alarms are NO JOKE when it comes to volume. The 125dB setting is absolutely ear-splitting - I tested one in my living room and my neighbor three houses down texted to ask if everything was okay! The chime mode is more bearable for everyday use though.

Installation couldn't be easier thanks to the strong 3M tape. I put these on all my ground-floor windows and my patio door within minutes. The adhesive is seriously strong - when I tried to reposition one, I nearly pulled paint off with it! Pro tip: Use goo gone if you need to remove them from finished surfaces.

Where these really shine is for travel security. I recently took them to an Airbnb and felt so much safer knowing I'd be alerted if anyone tried to enter. The alarms are small enough to pack easily but loud enough to wake the dead. Just remember to warn your travel companions before testing!

My only complaints? The on/off switch is nearly invisible (I had to mark mine with whiteout) and the alarm duration is shorter than I'd like. While they claim 30 seconds, mine cut off closer to 15. Not ideal if you're a deep sleeper.

For under $20 for 8 alarms, this is hands-down the most affordable security upgrade I've made to my home. They may not replace a full security system, but they provide excellent peace of mind - especially if you have kids or elderly family members who might wander.