Product review (3 stars): Work Well on Straight Tubes but not on Multi Corner Vents
If you have no tight bends or much built up, this brush may work well, but if you have the usual tight bends that a crawl space vent tube has, you will find this brush doesn't work for more than the first corner.  3 stars because it does work on the straight pretty well, but when it gets snagged, it tends to twist up really quickly with the drill, and can pinch you if not careful.