Yep 4" and it's double wall up the chimney not a liner, the pipe was cheaper than the liner and i've got a theory it probably cleans better or...
i've seen comments of beer, maybe discussion of cheese might bring more around I've never ran mine with the drill motor, just powered it by...
right back at ya
And if you use the fiberglass rods that screw together tighten them a bit more than finger tight, it's really inconvient when the brush unscrews...
Arti, is this what your looking for? It looks like the pic but no name on the add and maybe a bit pricey at $1400...