We have a pellet stove insert with a vertical run of about 20'. Despite what I thought about the completeness of combustion in a pellet stove, you do have to clean your chimney. This Vevor brand chimney brush worked worked in my 4\" stainless diameter chimney. Using a 1/2\" cordless drill to rotate the brush, knocked the combustion remnants to the clean out of the chimney for vacuuming. The sections of flexible rod provide easy extention to clean to the bottom of the chimney. A very nice kit for the job.