I've got 2 sockets, a 5/8 and a 13/16. Translates to a 15.875 and a 20.6375. Maybe you need the 13/16? Maybe a 3/4? Unfortunately mine are marked in standard, not metric. But it's easy enough to convert if you got a calculator handy.

I used the 13/16" to pull my plugs, so if they're the same plugs, it should work fine.