Product review (5 stars): You won't believe what lurks in your dryer vent
I purchased this product in preparation for a new dryer. I figured that after I had noticed birds nesting in my exterior vent opening I should give my duct a good cleaning--I am very glad I did. The operation of the product is simple--do be sure to note the instruction regarding NOT reversing the drill when pulling the cleaner from the vent when done cleaning (just leave it in the normal position as if you were driving a screw). Reversing the drill could cause the threaded joint fittings to come apart. The next important thing to note (as others have) is that you need to add/remove the links one at a time so that you don't have anymore than one or 1 1/2 not in the vent. If you have too many pieces together and not inserted in the vent it will whip around and damage the rod. I learned that the hard way but I blame it on myself.
On to the operation/result. I was blown away with the amount of straw and grass occluding my dryer vent at the exterior where the birds were. Once I cleared that obstruction I pulled tons of dryer lint out of the duct. I was astounded at how much crud was in there and preventing my dryer from working properly (as well as the potential for a dryer fire). This is a product that does what it says it will do and is well worth the money.