Product review (2 stars): Ripped apart a plastic section of tge duct.
I could not get it past a 90 degree turn. About 12 of 15 feet was aluminum duct and that was ok but the last 3 feet was plastic and wire and that was completely shredded.  I will be spending part of the weekend in a 18 inch crawl space replacing part of the duct. I will fix it but it was no blocked so good idea bad result.