Product review (5 stars): Excellent!
Excellent quality. Used this to clean out a dryer duct that had not been cleaned in 15 years. I can't imagine having done that with any lesser product. A couple of tips:

1. Be extremely cautious to not reverse the drill. You can tape the flexible shaft joints, but especially if you are cleaning out ducts that are well plugged, you will have to go in and back several times, and as you do so, you have to disconnect and reconnect the flexible shafts. I would instead tape over the reversing switch on the drill to stop yourself from accidentally reversing it.

2. Get yourself a good vacuum cleaner, like a shop vac, and position it at the duct outlet. Turn on the dryer to air fluff and start going in from the outside. As the accumulated lint is pushed out by the dryer air, it will make a big mess.

3. Carefully map out your duct system before you order. I assumed the duct was shorter than it turned out to be, and thought 12' would be sufficient. Turned out it was 17' and had to go finish it by cleaning out from the inside. I would rather have just gotten additional flexible shaft extensions.

4. Lightly grease the flexible shaft connections, or have on hand a couple of pliers to twist them back apart. The drill tightens them to the point that they cannot be easily disconnected by hand.

All in all this was just perfect for the job. I couldn't be happier.