Fender shields the control cavities on many of their guitars with shielding paint. The paint is sprayed into the cavities before the color or top coats are applied, so it's obscured. In order to be effective as a shield, this paint layer needs to be connected to ground.
The way Fender accomplishes this is to remove a small section of the top coat - exposing a small section of the shielding paint beneath - and then screwing this screw lug against the shielding paint that's been exposed. A wire that's soldered to the lug then has its other send soldered to ground - usually the back of a pot (the lug is tinned so it's very easy to solder to).
In some Teles Fender uses three of these lugs and screws: one in the control cavity, and one in each of the two pickup cavities. The three lugs are then connected together and one of them is connected to ground.
This is the exact lug Fender uses, and the exact screw size. We've soldered a 10" piece of 22 AWG stranded wire to it so that you can use it with our solder free components and not have to solder it yourself.