--- product_id: 650964047 title: "BlackT Electrotech (BT51D) 120dB Wireless Door Bell & Window Alarm Sensor – 4in1 Smart Calling Bell for Home, Office Cabin & Property Security – No Wire, Easy Installation" brand: "blackt electrotech" price: "€ 17.40" currency: EUR in_stock: true reviews_count: 8 category: "Blackt Electrotech" url: https://www.desertcart.gr/products/650964047-blackt-electrotech-bt51d-120db-wireless-door-bell-and-window-alarm store_origin: GR region: Greece --- # 4-in-1 multi-use security 120dB loud alert wireless, no wiring needed BlackT Electrotech (BT51D) 120dB Wireless Door Bell & Window Alarm Sensor – 4in1 Smart Calling Bell for Home, Office Cabin & Property Security – No Wire, Easy Installation **Brand:** blackt electrotech **Price:** € 17.40 **Availability:** ✅ In Stock ## Summary > 🚨 Secure your space, amplify your peace of mind! ## Quick Answers - **What is this?** BlackT Electrotech (BT51D) 120dB Wireless Door Bell & Window Alarm Sensor – 4in1 Smart Calling Bell for Home, Office Cabin & Property Security – No Wire, Easy Installation by blackt electrotech - **How much does it cost?** € 17.40 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.gr](https://www.desertcart.gr/products/650964047-blackt-electrotech-bt51d-120db-wireless-door-bell-and-window-alarm) ## Best For - blackt electrotech enthusiasts ## Why This Product - Trusted blackt electrotech brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Trusted & Tested:** Highly rated with 4.1 stars and proven battery longevity—security that keeps up with your lifestyle. - • **Instant 120dB Alert:** Cut through the noise with a piercing alarm that demands attention and deters intruders immediately. - • **4-in-1 Smart Security:** Seamlessly combines doorbell, window sensor, alarm, and emergency alert in one sleek device. - • **Compact & Modern Design:** Blends into any home or office aesthetic without bulky hardware or unsightly wires. - • **Effortless Wireless Setup:** Peel, stick, and secure—no electrician needed. Perfect for busy professionals who value time and simplicity. ## Overview The BlackT Electrotech BT51D is a wireless 4-in-1 doorbell and alarm sensor delivering a powerful 120dB alert to protect homes, offices, and cabins. Its no-wire installation and compact design make it ideal for quick setup and seamless integration, providing instant security notifications and deterring unauthorized entry with ease. ## Description Product Description Wireless Door Security Alarm Instant Security Alert System Wireless Alarm Protection System Protect doors and windows with instant wireless security alerts and loud alarm sound. Ideal for homes, offices, shops, apartments, and cabin security protection. Easy no-wire installation with reliable 120dB emergency alert system. Compact smart design delivers everyday safety with effortless operation. Get instant attention during unauthorized entry with powerful alarm protection. 1. How does the alarm detect door or window opening? The sensor and magnetic strip work together. When the door or window opens and the magnetic connection breaks, the alarm activates instantly. 1. How does the alarm detect door or window opening? The sensor and magnetic strip work together. When the door or window opens and the magnetic connection breaks, the alarm activates instantly. 2. How loud is the alarm sound? The alarm produces up to 120–125dB sound, helping alert occupants and deter unauthorized entry effectively. 2. How loud is the alarm sound? The alarm produces up to 120–125dB sound, helping alert occupants and deter unauthorized entry effectively. 3. Is wiring required for installation? No, it is completely wireless. Simply attach the sensor and magnet using the included adhesive for quick installation. 3. Is wiring required for installation? No, it is completely wireless. Simply attach the sensor and magnet using the included adhesive for quick installation. 4. Where can this alarm be used? It is ideal for homes, apartments, offices, cabins, shops, warehouses, windows, doors, and other entry points. 4. Where can this alarm be used? It is ideal for homes, apartments, offices, cabins, shops, warehouses, windows, doors, and other entry points. 5. Can it be used as a calling bell? Yes, its 4-in-1 design allows it to function as a wireless calling bell as well as a door and window security alarm. 5. Can it be used as a calling bell? Yes, its 4-in-1 design allows it to function as a wireless calling bell as well as a door and window security alarm. Home Security products BT51D 4-in-1 Door Alarm BT52DP WiFi Security Kit BT34S WiFi Motion Sensor BT31RW WiFi Motion Detect Review: must needed - must needed one for single man store owner , whenever someone opens the door it will give a heavy sound. i am using for 5 months battery is yet to replaced worth for money quality is too good Review: Useful 'Door Open' alarm - It is good for door open alarm/warning. It has 4 different settings, which are useful. The manual could be better designed but it is not difficult to figure out. ## Features - 🏠 [Wide Application – Home, Office & Cabin Use] Works as a wireless door bell for home, office cabin, or property security system. Perfect protection for doors, windows, and entry points without the need for wiring. - 🚨 [Enhanced Security – 4in1 Function] Acts as a wireless calling bell + alarm sensor to safeguard your loved ones. Deters intruders effectively while ensuring peace of mind. - 🔊 [125dB Loud & Clear Alert] Emits a powerful alarm sound that functions both as a door alarm security system and as an emergency alert bell. Guarantees instant attention during unauthorized entry. - 🛠️ [No Wire – Easy Installation] No complicated setup required. This wireless alarm bell installs in seconds—just peel, stick, and secure. Ideal for flats, cabins, shops, and offices. - 💡 [Smart & Reliable Design] Compact and versatile design fits seamlessly into modern homes. Doubles as a calling bell without wire while offering maximum protection with minimum effort. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B0DBJ2R2K4 | | Audible Noise | 120 Decibels | | Battery Description | Alkaline | | Best Sellers Rank | #4,861 in Home Improvement ( See Top 100 in Home Improvement ) #2 in Home Security Alarms | | Brand | Blackt Electrotech | | Built-In Media | magnet | | Colour | white | | Compatible Devices | Home Security System | | Control Method | Touch | | Country of Origin | China | | Customer Reviews | 4.1 out of 5 stars 83 Reviews | | Importer Contact Information | Blackt Electrotech | | Item Type Name | Door sensor | | Item Weight | 80 Grams | | Manufacturer | Blackt Electrotech | | Model Number | BT51D | | Mounting Type | Door Mount | | Packer Contact Information | Blackt Electrotech | | Power Source | Battery Powered | | Sensor Technology | Contact Sensor | | Size | Small | ## Product Details - **Battery Description:** Alkaline - **Brand:** Blackt Electrotech - **Colour:** white - **Compatible Devices:** Home Security System - **Power Source:** Battery Powered ## Images ![BlackT Electrotech (BT51D) 120dB Wireless Door Bell & Window Alarm Sensor – 4in1 Smart Calling Bell for Home, Office Cabin & Property Security – No Wire, Easy Installation - Image 1](https://m.media-amazon.com/images/I/51p8NfzarbL.jpg) ![BlackT Electrotech (BT51D) 120dB Wireless Door Bell & Window Alarm Sensor – 4in1 Smart Calling Bell for Home, Office Cabin & Property Security – No Wire, Easy Installation - Image 2](https://m.media-amazon.com/images/I/71yz+WNelLL.jpg) ![BlackT Electrotech (BT51D) 120dB Wireless Door Bell & Window Alarm Sensor – 4in1 Smart Calling Bell for Home, Office Cabin & Property Security – No Wire, Easy Installation - Image 3](https://m.media-amazon.com/images/I/81AH9uRM7dL.jpg) ![BlackT Electrotech (BT51D) 120dB Wireless Door Bell & Window Alarm Sensor – 4in1 Smart Calling Bell for Home, Office Cabin & Property Security – No Wire, Easy Installation - Image 4](https://m.media-amazon.com/images/I/71abKv3SvTL.jpg) ![BlackT Electrotech (BT51D) 120dB Wireless Door Bell & Window Alarm Sensor – 4in1 Smart Calling Bell for Home, Office Cabin & Property Security – No Wire, Easy Installation - Image 5](https://m.media-amazon.com/images/I/71oFOWTT4bL.jpg) ## Questions & Answers **Q: 1. How does the alarm detect door or window opening?** A: The sensor and magnetic strip work together. When the door or window opens and the magnetic connection breaks, the alarm activates instantly. **Q: 2. How loud is the alarm sound?** A: The alarm produces up to 120–125dB sound, helping alert occupants and deter unauthorized entry effectively. **Q: 3. Is wiring required for installation?** A: No, it is completely wireless. Simply attach the sensor and magnet using the included adhesive for quick installation. **Q: 4. Where can this alarm be used?** A: It is ideal for homes, apartments, offices, cabins, shops, warehouses, windows, doors, and other entry points. **Q: 5. Can it be used as a calling bell?** A: Yes, its 4-in-1 design allows it to function as a wireless calling bell as well as a door and window security alarm. ## Customer Reviews ### ⭐⭐⭐⭐⭐ must needed *by S***I on 28 July 2026* must needed one for single man store owner , whenever someone opens the door it will give a heavy sound. i am using for 5 months battery is yet to replaced worth for money quality is too good ### ⭐⭐⭐⭐ Useful 'Door Open' alarm *by N***A on 18 May 2026* It is good for door open alarm/warning. It has 4 different settings, which are useful. The manual could be better designed but it is not difficult to figure out. ### ⭐⭐⭐⭐⭐ Good Product *by S***G on 29 May 2026* Product working flawlessly ## Frequently Bought Together - Blackt Electrotech (BT51D) 120dB 4in1 Wireless Door and Window Alarm Sensor for Home and Property Security - Blackt Electrotech BT51A Wireless Motion Sensor Alarm with Intelligent Welcome Doorbell, Infrared Detector, Gate Alert Alarm, Remote Control, Easy Install for Daily Safety Protection --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.gr/products/650964047-blackt-electrotech-bt51d-120db-wireless-door-bell-and-window-alarm](https://www.desertcart.gr/products/650964047-blackt-electrotech-bt51d-120db-wireless-door-bell-and-window-alarm) --- *Product available on Desertcart Greece* *Store origin: GR* *Last updated: 2026-08-12*