ALMOCN 3pcs HC-05 Wireless Bluetooth RF Transceiver Master Slave Integrated Bluetooth Module 6 Pin Wireless Serial Port Communication BT Module for Arduino

There seem to be two flawed variants of these boards being sold on all the normal sites. In this case this supplier supplied the two smaller chip at the top variety and not the larger chip version in their photo even though I doubt they would overly know one from the other. These pretend to be HC-05 when you interrogate the chip via the AT commands however they refuse to change into master mode. I would have returned them however I thankfully bought some from a previous supplier that operated as HC-05 and worked in both master and client mode but with other issues!As a client (in effect HC06 device), allowing an Arduino/Pi to connect to a master device - maybe a phone these will work fine.For completeness the version in this suppliers description (second photo with the larger top chip) do work in Master mode however 1) they won't allow the password to be changed 2) they allow auto connection of a known slave device however incorrectly if they do not see a connection soon they will allow any device to connect to them which is a (security) fault.However in summary, the device provided was not a functional HC-05 (master mode) device and hence the rating.