‘Shims’ for the Espruino Pico are small adaptor boards that you can solder to the Espruino Pico to make it easier to attach devices. For example: WIZnet WIZ550io Module
In order to use WIZ550io in Espruino, you had to connect with wire. Like the picture below :
However, if you use Shims, you can connect WIZ550io directly to Espruino.
The Shim available for the Espruino Pico helps to adapt the W550io to fit onto the Pico. Please see the video below: