Review on DSD TECH HC-05 Bluetooth Serial Pass-through Module: Seamless Wireless Serial Communication with Arduino Button by Los Bizness

You can buy the HC-05 from various vendors, some at significant discounts, but they usually come flashed with newer firmware versions that are not as reliable and tested as those supplied by DSD-Tech. I recently bought four HC-05s from another supplier for about the same price as DSD-Tech; Connection problems, pairings are lost and the device crashes during data transfer. Finally I decided to replace the devices with DSD-Tech modules and now the system works perfectly. No other changes, only HC-05 changed.