Product review (1 stars): Don't bother with it
Cheaply made in China.  6-inch brush attachment sheared off, at the attachment point. I put one rod (out of possible four); with the attached rotary 6-inch brush.  Rotated and inserted it as specified into the vent exhaust pipe. It went easy past the first elbow.  I then tried to retrieve it as the insertion was close to the end of the rod and the 6-inch brush remained inside.  Had to call a specialist to retrieve the brush and complete the cleaning...and off course paid for it.  The only good thing that came out of this is the learning curve...leave this kind of job to the professional.