very easy to clean
Northline service folks recommended this one for the exact flue dimensions I provided. Just cleaned both flues. Very easy. Internet search results suggest hiring someone costs $79-$200. That's more than the total cost for the rods and brushes. The picture shown doesn't represent well the accurate shape of this product, but it fit very well in my 6"x10" rectangular flue. 10 minutes the job is done.