They report an opening, which is earlier than reporting a presence · review
Fifteen alarms for twenty-one dollars, which is the cheapest way on this shelf to put something on every opening in a house.
The conclusion Fifteen alarms for twenty-one dollars is about a dollar forty each, which makes covering every opening in a house a decision you do not have to think about — and this shelf's introduction is right that a contact on the window reports earlier than a detector reporting a presence. Budget another ten dollars for thirty AAA cells, which are not supplied. No dimensions on a fifteen-unit install is the real omission, and like five of seven here it alerts nobody but the room.
No gap figure. No dimensions. No battery life. No tamper detection.
Front door, back door, patio door, eight to ten windows.
A dollar forty each, so the marginal cost of covering a bathroom window is nothing.
The alternative on this shelf is three five-packs.
Which are not in the box, and which the price does not include.
Two per unit, fifteen units. Perhaps ten dollars.
A twenty-one dollar purchase is a thirty-one dollar purchase. Buy them with it.
And tells the house. It does not tell the street.
Ninety at arm’s length is about a hairdryer: unpleasant, audible through a closed internal door, audible from the garden.
Enough to move an opportunist off a ground-floor window and to wake someone upstairs.
The 120 and 125 dB units on this shelf are the ones meant to carry across a street, and they cost four to seven dollars each.
Not a phone alert.
A sealed box with a magnet, taped on, two AAA cells. No radio, no app, no hub.
At least five of the twelve sensors here work this way, and all five use the word.
The two Ring sensors are the ones that report to a system, at ten to thirteen dollars each and an account.
Which is the real omission on a fifteen-unit install.
Two of the cheaper sirens on this shelf publish theirs — 3.4 × 1.1 × 0.6 inches and 3.54 × 1.18 × 0.79.
Across fifteen different frames, body size is the thing most likely to stop one of them fitting.
On sale at around $21 on the American Amazon store at the time of checking.
Prices and availability are what Keepa reported on the date this page was updated; both move.
Prices quoted in this text were read on October 8, 2026. The live price is at the top of the page.
| Supplied | Fifteen alarms, stated — the largest pack on this shelf by a factor of two and a half, at about a dollar forty each. The next largest is a six-pack |
|---|---|
| Type | A standalone alarm: the magnetic switch detects the opening, the unit sounds at 90 dB where it is stuck, and nothing is reported anywhere else. No app, no radio, no base station |
| Volume | 90 dB, stated. The lowest tier on this shelf, where two units reach 120 and 125 dB |
| Power | Two AAA cells per unit, stated NOT included. Fifteen units is thirty AAA cells to buy before anything works, which is a real cost against a twenty-one dollar price |
| Mounting | Adhesive, with an on/off switch pressed before the cells go in, then the double-sided tape peeled and the unit stuck to the frame — stated |
| Applications | Homes, apartments, offices, hotel rooms and garages, stated, with child safety named: preventing children and babies leaving the house |
| Gap tolerance | Not published. One listing on this shelf publishes a figure — 0.6 in — and this shelf's introduction calls it the specification that decides whether a sensor works at all |
| Dimensions | Not published, where two of the cheaper sirens on this shelf publish theirs. On a fifteen-unit install across different frames, the body size is the thing most likely to cause a problem |
| Tamper | Not published, as on every listing on this shelf |
| Amazon reference | B0BRN8R4HG |
| EAN | 0774947806321 |
For most houses it is about right, which is the point. An ordinary three-bedroom house has a front door, a back door, a patio door and eight to ten windows — and the honest alternative on this shelf is buying three five-packs. At a dollar forty each the marginal cost of covering a bathroom window is nothing, and this shelf's introduction is right that a contact on the opening reports earlier than a motion detector reporting someone already inside. The caveat is thirty AAA cells, which is perhaps ten dollars and turns a twenty-one dollar purchase into thirty-one.
It startles, and it tells the house. Ninety decibels at arm's length is about as loud as a hairdryer: unpleasant, clearly audible through a closed internal door, and audible from the garden. That is enough to make an opportunist leave a ground-floor window and enough to wake someone upstairs. What it is not is a deterrent across a street, which is what the 120 and 125 dB units on this shelf are for — and those cost between four and seven dollars each rather than a dollar forty.
No, and this is the most common misreading on this shelf. Wireless here means there is no cable to run — the unit is a sealed box with a magnet, stuck on with tape, powered by two AAA cells. There is no radio in it, no app, no hub and no phone alert. At least five of the twelve sensors on this shelf work this way, and all five use the word. The two Ring sensors here are the ones that report to a system, and they cost between ten and thirteen dollars each and need an account.
Between security devices of the same category and nearby price. Shown: what they all state. A half-filled column says nothing.
| Model | Price | Type | Applications |
|---|---|---|---|
| WimuPath Door and window alarm, 15-pack, 90 dB | $21 | A standalone alarm: the magnetic switch detects the opening, the unit sounds at 90 dB where it is stuck, and nothing is reported anywhere else. No app, no radio, no base station | Homes, apartments, offices, hotel rooms and garages, stated, with child safety named: preventing children and babies leaving the house |
| Philips LRM3320W/27 window and door alarm, 4-pack, 120 dB with chime mode | $19 | A standalone alarm with a magnetic sensor: it sounds where it is fitted and reports nothing remotely. No app, no radio, no base station | Windows and doors, stated. Four units per pack for extra coverage |
| HENDUN SZSF03R | $10 | Standalone magnetic contact alarm | Doors, gates, windows, pool gates, per HENDUN |
| KOLODOGO Door and window alarm, 5-pack, 90 dB, 3.54 × 1.18 × 0.79 in | $10 | A standalone alarm: the magnetic sensor triggers a 90 dB siren in the unit itself, and nothing is reported remotely. No app, no radio, no base station — Wireless in the title means no cable to run | Home, apartment, office, garage and hotel, stated, and named for monitoring children and pets or preventing access to dangerous areas as well as burglary. Stated to attach to door knobs, window frames or be carried |
Details checked on October 8, 2026.
A whole house, a vacation rental or a small office where every window should make a noise and nothing needs an app
Amazon reports what buyers took in the month before this page was last checked: at least 400.
The figure is a floor, rounded by Amazon, and read through Keepa — it says what buyers picked, not what a maker claims.
Specifications: the manufacturer sheet for home security products and the matching Amazon product page. Prices and availability: Keepa. Every figure on this page names its source.
For Smartvest Pro · wireless opening detector · triggers configured scenarios · doors and windows
The opening detector for ABUS's Smartvest Pro alarm. It reports unauthorized opening of doors, windows and patio doors, and triggers whatever scenarios have been configured on the panel.
Best for: An ABUS Smartvest Pro system being extended door by door.
90 dB standalone siren · 3.54 × 1.18 × 0.79 in and about 0.08 lb, both published · 2 AAA, NOT included · a three-step install written out · five units for ten dollars · no gap figure, no battery life, no tamper detection
Five alarms for ten dollars with their dimensions and weight published — two figures the cheapest sirens here usually leave out.
Best for: Five openings on a tight budget, where the body has to be measured against a shallow frame first
≈ $10
120 dB alarm or chime, switched on the side: OFF / chime / alarm · 4 LR44 cells SUPPLIED · a battery TEST BUTTON and a low-battery LED, the only test button on this shelf · double-sided tape included · no gap figure, no battery life, no tamper detection
The only sensor here with a button that tells you the battery is still good — which on an alarm nobody checks is worth more than it sounds.
Best for: A household that wants a chime for the back door in the day and an alarm on it at night
≈ $19
