arre Contact Sensor

A tidy door trigger, with a price premium to justify

The arre Contact Sensor is most appealing on a visible door or window where a larger battery housing would look clumsy. Its main body measures 40 × 31 × 13 mm, with a separate 15.5 × 40 × 13 mm magnet. The rounded white casing is fairly discreet, and the included CR2032 is a familiar battery to replace.

Its everyday job is simple: opening a closet can turn on a light, or opening a window can pause suitable heating through an automation. It reports whether the two pieces are together. It does not tell you whether the door is locked or whether someone remains in the room.

The frame is the reason to choose it

The removable backplate can attach with screws or adhesive, giving you a choice between a more permanent fixing and avoiding holes. Rear battery access also means the sensor needs to remain removable after mounting. A flush-looking installation that traps the cover behind trim is not a useful improvement.

arre's checked material does not specify a maximum operating gap between magnet and sensor. That makes a deeply recessed frame a less confident purchase than an ordinary pair of nearby, aligned surfaces. The claim that it fits most frames is too broad to settle that question.

Aqara Door and Window Sensor P2 includes a thin alternative magnet, while Eve Door & Window includes magnet spacers. Those physical provisions can justify paying more when the frame is awkward. We would not choose arre simply because its casing looks smaller in a photograph.

An easy battery to buy, an unclear interval to expect

The current store estimates about two years from the included CR2032. arre's linked support page mixes an expectation of over two years with an advertised one-year figure depending on use. The useful certainty is the replaceable battery format; the replacement interval is not established by those conflicting claims.

We have not measured battery life or state-reporting delay. Keep rear access practical and pay attention to low-battery reporting in the app you use. There is little value in a discreet sensor that becomes awkward to maintain on a frequently opened door.

Only white was selectable in the current store. Copy mentioning a black finish is not an available black purchase option.

The household app supplies the convenience

The sensor joins Matter over Thread without an arre hub. A compatible Matter controller and Thread border router still need to serve the frame. This is most economical when that infrastructure already exists; buying it solely for one contact sensor changes the purchase considerably.

Apple Home, Google Home, Alexa and SmartThings are listed. Notifications, event history and the action taken after a door opens come from the chosen platform. The sensor has no local siren, and a reported open state alone does not guarantee the household receives the particular alert it expects.

Compare the complete price

On September 10, 2026, the white sensor was $23.99 in arre's US store, against a $29.99 regular price. One sensor falls below the advertised $75 free-shipping threshold, so delivery and tax remain extra. The published shipping-policy page did not provide the single-order delivery charge.

IKEA MYGGBETT was listed at $11.99 US before its required AAA battery and any delivery. It is a stronger budget starting point when its tight closed gap of less than 5 mm fits the frame. arre's coin cell and compact casing are reasons to compare the actual installation, rather than assume it wins on price.

Choose arre when its shape, battery format and fixing method are a good match. Keep an existing contact sensor if it already reports reliably and mounts neatly. Replacing it for a different protocol alone does not improve the door routine.