4" Thumper access upgrade from 3"
If you think that 3" is not large enough for you to get in and do your business, you can upgrade to a 4" opening with larger collar and matching hardware to make your life easier.
The upgrade from 3" to 4" can make your life easier. You can also put the head from the still on the thumper and run it that way too. Matching 4" hardware gives you even more flexibility to your project.
4" copper Collar upgrade from 3"
4" stainless lid
4" stainless clamp
4" silicon Gasket