Product review (4 stars): great tool! did a very thorough job
This tool worked really good and now I feel so much better knowing my dryer vent is finally clean!  Ensuring you only spin the tool in the clockwise direction is important, though -- but even doing that I'd still be cautious.  They recommend using duct tape to secure the connections, but even that is not fool-proof; the connections are probably this tool's only lacking feature.  But if you are careful, you should be ok -- I only used it by hand to clean out the back pipe area of the dryer and the hose area to the outside.  It did a great job, plenty of length for my dryer -- there did not seem to be any need to use a drill.  The bristles are stiff and strong -- just what you need to do the job right.