Review on 4-Pack 3.3V 5V FT232RL USB to TTL Serial Converter Adapter Module for Arduino by Ron Patel

Well they work. If you plan on just using them alone, that's fine. A bit annoying is that the ft232rl chip is fake. I'd like to know how they get away with it. I don't know if that's better, but other Chinese suppliers tell you that this part is not genuine. The FTDI part has an onboard EEPROM that can be programmed, but not, or at least not, with the software provided by FTDI. You have to be careful. Windows requires a unique serial number if you want to assign a specific port number to a specific device. They all have the same serial number. Since the VID and PID are the same as they should be, the lack of a unique serial number means Windows cannot tell them apart. As far as I can tell this cannot be fixed by plugging them into the network in any particular order. However, if you are predisposed, you can buy them and replace the chip with a legitimate version. You can still save a few dollars by purchasing a unit with a genuine FTDI part.