What size?

I have always used the 15/16th socket, with a small extension.

The wrench that comes with those plugs has two different sizes. I would think that implies there are two different size plugs out there. At least on the outside. The inside diameter of the drain may be the same on all water heaters. I increased the bend angle on that tool and it worked just fine. Channel Lock pliers have worked also.

I would try the socket first as I did but it was a no go,So I went with This One and it worked out very well.

There are diffrent ones, look up the make and model of your heater and match it. I use a short extention on my socket.

Always good to have an extra plug but thirteen bucks for a bent piece of metal?