Product review (4 stars): Now the drier blows out with good volume at the outlet
At first this thing did not appear to work.  I could not get it to feed into a straight dyer vent pipe more than about 16 inches.  But kept working it in and out without using any sort of power drill.  Just turned the supplied crank handle.  Turned the drier on.  Kept working.  Eventually pulled out huge gobs of drier lint.  That was why it would not feed!  Holy cow I had no idea there would be so much lint in there..  Kept working and working in and out, turning minimally but did keep feeding and turning.  Pulled entire feed line out 4-5 times. Eventually got the entire vent pipe cleared.  All ten feet of it.  Total haul:  about 1/2  a trash bag full.  Now the drier blows out with good volume at the outlet.  Four stars because the drive line is a bit fragile. I have recent experience with a roto-rooter unit, so have a basis for comparison.  Also, the directions for use are seriously lacking  Nevertheless, for occasional handy man use, this is well worth the cost.