zoethecus stand - what size cone feet?

I have a zoethcus stand with five black slabs (including the top one) I picked up a while ago. It did not come with feet but has the threads for it.

Does anyone know what size adjustable cones would fit those?

I was going to get cones and the little washer things for the cones to stand on. That's my current set up for my speakers. Assuming that is recommnedable for the stand as well?

Thanks very much.
Mine are about 2 1/4 inches tall and 1 inch wide at the base.
Hi Pima,

I happen to have a set of Zoethecus cones, pm me with an offer if you're interested.

Thanks Uru975. Would you happen to know where you got them?
They came with the rack. Send me your email and I'll send you a picture. That should at least show you what they look like.
There are three possible thread sizes: 1/4", 3/8" or 5/16". Go to a hardware store and buy three 1" bolts of each thread size. Once you know the correct size you I suggest using brass Audio Points - model 2.0 AP.
Thanks so much! I will do that and post here what I found out.
The thread size is 5/16-18.
I can confirm that 5/16 is the correct size.