Product review (5 stars): This thing works if used in the right way.
The vent in my house is about 14 feet long. So I had to buy another set.
My vent as got 100% blocked when tried to use a blower. I then used this device and all the clog came closer to inside wall.
Used a vacuum cleaner to suck up all clog and then used this device again. Repeated brush, vacuum and blower about 3 to 4 times and the vent is now clean.
By its self it may not work all the time if your clog is bad.
But it does work and for the price, it is defiantly worth it. Just be careful to never rotate it in the counter clockwise direction (unscrew direction). If you do that, one of the links may disconnect and the whole thing may get stuck in the vent which would be a total nightmare.