[Pepper (Steve)]

I have a half pillar extension on my pier for my neq6.
I would like to go just a bit higher and was wondering if anyone can tell me if I buy the 40 cm extension (which is advertised as a heq5 extension) is the same except for height and the top part.
Can I swap my neq6 top onto the taller tube.( basically are they the same inside diameter?)
Thanks