This is an adapter that allows a serial Weatherlink logger to connect to a USB port on a PC and typically used for a modern PC which has no serial ports. Driver are available for most popular operating systems. This is a good-quality part which we know works with the Davis loggers, unlike cheaper alternatives which can be very hit or miss as to whether they will work robustly.
Note: This adapter does require a driver. On many modern operating systems a good driver is already installed as part of the operating system, but sometimes a new driver or an update may need to be downloaded.