Entry Detection That Installs in Under Two Minutes
A door or window alarm doesn’t need to be complicated to do its job. The magnetic sensor principle is straightforward: two halves stay close together, alarm stays quiet. The moment they separate — because a door or window is being opened — the circuit breaks and the siren sounds. The Safety Technology magnetic alarm handles this reliably, adds a manual on/off switch for your own use, and requires nothing more than peeling off an adhesive backing to install.
Who This Door and Window Alarm Is For
Renters and apartment dwellers who want entry detection without drilling, patching, or risking a security deposit will find peel-and-stick installation removes every obstacle to getting it done. Parents who want to know when a door or window is being opened — whether by a young child or an unwanted visitor — get a direct, audible alert at the point of entry without any monitoring subscription. Homeowners adding basic coverage to secondary entry points like basement windows, garage doors, or back doors get an affordable option that’s quick to deploy and doesn’t require any wiring or technical setup.
Is This the Right Choice for You?
Choose the Magnetic Door/Window Alarm if you want:
- Immediate audible alert when a door or window is opened without authorization
- Dead-simple peel-and-stick installation with no tools or technical knowledge required
- A manual on/off switch so you can open windows yourself without triggering the alarm
- An affordable two-pack to cover multiple entry points in one purchase
Consider something else if you need:
- Detection of glass breaking without the window being opened — a glass break vibration alarm covers that
- Interior room coverage after entry — a motion sensor or barking dog alarm is better suited
How It Actually Works
The alarm consists of two pieces. The larger piece — containing the alarm circuit and battery — mounts to the door or window frame. The smaller magnetic piece mounts to the door or window itself. When the door or window is closed, the two pieces sit next to each other and the magnetic connection keeps the circuit intact. The moment they separate, the 90dB siren activates.
The on/off switch is a practical addition that makes this alarm livable on a window you actually want to open sometimes. Switch it off before opening, then switch it back on when you close it. It’s a small thing, but it’s the difference between a security tool you use consistently and one you disable permanently because it’s inconvenient.
At 90dB, the alarm is in the range of a lawn mower or a passing motorcycle at close range — clearly audible through walls and across most residential spaces. The unit measures 2.5″ x 1.75″ x 0.75″ and the three LR44/AG13 batteries that power each unit are included in the pack, so you can install both alarms immediately without a separate battery run.
Quick Comparison: How Does the Magnetic Door/Window Alarm Stack Up?
| Feature | Magnetic Door/Window Alarm | Glass Break Alarm | Motion Sensor | Barking Dog Alarm |
|---|---|---|---|---|
| Triggers On | Door/window opening ✓ | Glass impact/vibration ✓ | Movement in room ✓ | Movement through walls ✓ |
| Works on Doors and Windows | Yes ✓ | Windows only | No | No |
| On/Off Switch for User Access | Yes ✓ | No | Usually | Yes |
| Installation | Peel-and-stick ✓ | Peel-and-stick ✓ | Mounting required | Plug-in or battery |
| Detects Entry Before Intruder Is Inside | Yes ✓ | Yes ✓ | No — after entry | Before entry ✓ |
| Best For | Point-of-entry door/window detection | Glass break at windows | Interior movement | Perimeter deterrence |
Practical Details
Each alarm measures 2.5″ x 1.75″ x 0.75″ and weighs 0.2 lbs. Runs on three 1.5V LR44/AG13 button cell batteries (included in each unit). Alarm output is 90dB. Built-in on/off switch. Peel-and-stick adhesive included. Color: white. Two alarms per pack. 1-year warranty. Manufactured by Safety Technology.
Two entry points, two alarms, batteries in the box — you can have both units installed and armed in the time it takes to read this page.
Frequently Asked Questions
How far apart can the two magnetic pieces be before the alarm triggers?
The magnetic sensor is designed to trigger when the two pieces separate beyond a very small gap — typically within a fraction of an inch of separation. This means the alarm fires at the very beginning of the door or window being opened, not after it’s partially open. For proper function, both pieces should be mounted close together when the door or window is in the closed position — ideally with the faces nearly touching or within about an eighth of an inch of each other.
Can I use this on a sliding glass door?
Yes. Sliding glass doors are one of the most common applications for this type of alarm. Mount the alarm body to the door frame and the magnetic piece to the door itself, positioning them so they’re aligned when the door is fully closed. The on/off switch is particularly useful here since sliding glass doors are often opened intentionally during the day. Switch it off when you’re using the door, back on when you close up for the night — takes two seconds.
Does the alarm stay on continuously after triggering, or does it stop on its own?
The alarm continues sounding as long as the magnetic pieces remain separated. When the door or window is closed — returning the two halves to proximity — the alarm stops. This means if you trigger it by accident, simply closing the door or window ends the alarm immediately without needing to touch the unit. For persistent intrusion attempts, the alarm continues until the entry point is secured.
How long will the batteries last?
LR44/AG13 button cells have good standby longevity — in a sensor that’s armed but not actively alarming, expect a year or more of battery life under typical conditions. Frequent triggering will drain them faster, but for a standard residential installation that sets off occasionally, annual battery replacement is a reasonable maintenance schedule. Replacement batteries are inexpensive and available at most hardware stores, pharmacies, and online.
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