Product review (5 stars): If you don't like paying someone every year to clean your dryer vent
I needed a way to clean out my vertical dryer vent duct. I attached this to my cordless drill and cleaned the duct out, scrubbing maybe 3-5 feet of the duct at a time before backing the brush completely out and vacuuming up everything that had fallen out. I made sure to follow the instructions and didn't rotate the pole the wrong direction, and the poles all stayed together as advertised. Cleaning the duct myself wasn't nearly as laborious as I thought it would be.

I went about 3 years before buying this to clean my dryer vent/ducting. Frankly, I'm surprised my house hadn't caught fire based on how much lint came out! If you don't like paying someone every year to clean your dryer vent, but you also don't want to die in a fire, I recommend buying one of these.