Anode Hex Key Size (cavitation plate)

[Weave]

I'm changing my anodes and forgot to bring an allen wrench.....Does anyone know what size wrench is needed to cahnge the anode on the bottom of the cavitation plate?

 

[Bt Doctur]

Gen II may not be a allen. 5/16 or 3/8 fit most. Just serviced one that had a 1/2 hex head bolt., not an allen head.