HiLetgo HC-06 RS232 4 Pin Wireless Bluetooth Serial RF Transceiver Support Module Slave and Master Mode for Arduino

Programming the HC-06 was fairly easy to do. The one thing to remember is that these are slave-only mode, so you can't use them as masters. Which is fine for most embedded projects out there. As a result, the HC-06 uses only a subset of the AT commands for programming, such as setting the name, PIN, and baud rate but not being able to get them out of the device's EEPROM.The range is typical of most Bluetooth devices out there, barring any kind of interference by structures or otherwise. Runs on 3.3V and is well-behaved from what my meter showed, as it was able to sleep with only minimal current drain on the board.I used this in an Arduino Nano project, which I later transferred to a Teensy 3.6. It was practically seamless jumping from one to the other. I used the SoftwareSerial library for UART communication. After about 15 minutes of fiddling around with it on both boards, I was able to talk to it using my smartphone and my laptop.

Does not work with iOS devices. Just won’t! Look it up if you were planning on using with an iOS device!

This gets good range and works great! Keep in mind this does need to be sent a few AT commands to get it set up. I've used it to tune a flying quadcopter, so I have no complaints.

I bought two of these units and BOTH of them are not working :(The one is completely dead.. And the other one wont transmit.. (it can only receive)I have other of the same kind and they work fine...

I purchased this to add Bluetooth connectivity to the laser engraver I have. For this it works OK. The documentation was a little poor as some of these ship with different revs of the firmware - but over all they work as advertised.