---
product_id: 650964047
title: "(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: "$18.12"
currency: USD
in_stock: true
reviews_count: 8
category: "Blackt Electrotech"
url: https://www.desertcart.us/products/650964047-bt51d-120db-wireless-door-bell-and-window-alarm-sensor-4in1
store_origin: US
region: United States of America
---

# 4-in-1 multifunctional security 120dB loud alert wireless, no wiring needed (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:** $18.12
**Availability:** ✅ In Stock

## Summary

> 🚨 Secure smarter, not harder — your silent guardian with a loud voice!

## Quick Answers

- **What is this?** (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?** $18.12 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/650964047-bt51d-120db-wireless-door-bell-and-window-alarm-sensor-4in1)

## 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

- • **Instant 120dB Alert:** Cut through the noise with a piercing alarm that demands attention.
- • **Versatile Placement:** Perfect for homes, offices, cabins, and any entry point needing smart protection.
- • **4-in-1 Smart Security:** Doorbell, alarm sensor, remote activation & adjustable sensitivity all in one sleek device.
- • **Compact & Modern Design:** Blends seamlessly with your space while delivering maximum security impact.
- • **Effortless Wireless Setup:** Peel, stick, and secure—no electrician required, no wires in sight.

## Overview

The BlackT Electrotech BT51D is a cutting-edge 4-in-1 wireless door and window alarm sensor delivering a powerful 120dB alert. Designed for easy, wire-free installation, it combines doorbell functionality with advanced security features, making it ideal for homes, offices, and cabins. Compact yet versatile, it ensures instant notification of unauthorized entry, empowering you with peace of mind and modern protection.

## Description

Product Description Blackt Electrotech (BT51D) 120dB 4-in-1 Wireless Door and Window Alarm Sensor for Home and Property Security The Blackt Electrotech (BT51D) 120dB 4-in-1 Wireless Door and Window Alarm Sensor is an essential security device designed to protect your home and property from unauthorized access. Combining four advanced security functions in one compact unit, this alarm sensor ensures that your doors and windows are safeguarded with ease. Featuring a loud 120dB alarm, this device alerts you immediately to any breach, providing peace of mind whether you are at home or away. Ideal for Homes, Apartments, and Offices The BT51D is perfect for use in homes, apartments, or offices, offering reliable security for a wide range of spaces. Protect your doors, windows, garage entrances, or any other vulnerable access points with this versatile and easy-to-install wireless alarm sensor. Whether you live in a house or a flat, the BT51D provides the reliable protection you need for peace of mind. 4-in-1 Multifunctional Security System The BT51D is equipped with four key security features: a door/window sensor, alarm system, remote control activation, and adjustable sensitivity settings. It offers complete versatility, allowing you to configure the system to meet your specific security needs. You can place it on doors, windows, or other entry points around your home to keep your property safe from intruders, ensuring that any unauthorized entry will trigger an immediate alarm.

Review: Great product - Working great. And has 4 modes. 2 modes with siren type sound alerting everyone. Other 2 has single doorbell type warning sound and beep sound. So both loud and soft sounds present so can be used in day to day purpose
Review: Good quality and VERY loud, however - The first time I ordered, desertcart sent me a different product but the next time they sent the right one. The box is small and contains the main unit, the magnet and a few double sided tapes for installation. There are 4 modes is this as indicated in the video in the product description. However, the Chime mode doesn't sound as shown in the video. It doesn't really Chime but Beeps loudly two times. I had expected that the chime mode would be like as shown in the video, like doorbell sound. The product build quality is good. Let's see how long it works.

## 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 | #8,987 in Home Improvement ( See Top 100 in Home Improvement ) #8 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 | 3.9 out of 5 stars 60 Reviews |
| Importer Contact Information | Blackt Electrotech |
| Item Type Name | Door sensor |
| Item Weight | 80 Grams |
| Manufacturer | Blackt Electrotech |
| Mounting Type | Door Mount |
| Packer Contact Information | Blackt Electrotech |
| Power Source | Battery Powered |
| Sensor Technology | Contact Sensor |

## Product Details

- **Battery Description:** Alkaline
- **Brand:** Blackt Electrotech
- **Colour:** white
- **Compatible Devices:** Home Security System
- **Power Source:** Battery Powered

## Images

![(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)
![(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)
![(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)
![(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)
![(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)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Great product
*by P***R on 7 March 2026*

Working great. And has 4 modes. 2 modes with siren type sound alerting everyone. Other 2 has single doorbell type warning sound and beep sound. So both loud and soft sounds present so can be used in day to day purpose

### ⭐⭐⭐⭐ Good quality and VERY loud, however
*by P***. on 4 November 2024*

The first time I ordered, Amazon sent me a different product but the next time they sent the right one. The box is small and contains the main unit, the magnet and a few double sided tapes for installation. There are 4 modes is this as indicated in the video in the product description. However, the Chime mode doesn't sound as shown in the video. It doesn't really Chime but Beeps loudly two times. I had expected that the chime mode would be like as shown in the video, like doorbell sound. The product build quality is good. Let's see how long it works.

### ⭐⭐⭐⭐⭐ Good product
*by C***A on 22 January 2026*

Good product

## 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

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*Product available on Desertcart United States of America*
*Store origin: US*
*Last updated: 2026-05-16*