Feature：This is the paired version of the BT27-A master-slave module, which includes one master bluetooth module and one slave bluetooth module. It has been paired and can be directly connected after being powered on. Note: The master module can only be connected with the slave modules sold in our store, and cannot be connected with any other model Bluetooth module. | Multiple Connection Methods：1. Can search connection Manually; 2. With MAC address code, it can scan QR code for connection. Compatible with Android/iOS. Please note that the slave module cannot communicate directly with the computer. It requires the master module to connect to the computer and use the computer serial port assistant to communicate with the slave module. | Long Range：The connection distance between the BT27-A slave and the mobile phone can reach 150 meters, and the connection distance between the BT27-A master and the BT27-A slave can reach 420 meters(This distance data is the result of testing in an unobstructed and open area. If it is not within the visible range during use, please use the measured results as the main one.). Module size 37.5(L) x 15.7(W) x 4.0(H) mm.Bluetooth BLE 5.1 protocol. DIALOG 14531 main control chip+PA amplifier. Transmission rate 10K Bytes/s. Operating temperature - 40 +85 ℃. Supports UART hardware interfaces. | Wide Application：You can quickly add Bluetooth functionality to your Arduino project, and then you can use an Android/iOS phone to control some small tools. This module is mainly used for wireless transmission of short-range data, such as Bluetooth wireless data transmission, smart home, intelligent educational devices, device monitoring and wireless control, measurement and monitoring systems, industrial sensors and controls, tracking and positioning. | Customer Service：Our products have multi-layer packaging protection: needle guiding sponge, electrostatic bag, packaging bag. It can maximally prevent the product from being damaged during transportation. Out of the box, plug and play. In addition, we provide English technical manual electronic document for customer research. If you encounter any issues, please contact us, and we will resolve your issues within 24 hours.