Oh, I think it’s about the same as butyl or somewhat better. Puncture resistance for me is probably more a function of the tire than the tubes. However, I had more issues flatting with early Tubolitos than with the Aerothans (non-puncture quality issues with the early Tubolitos) and the Aerothans have none of that. I don’t ride TPU tubes for flat resistance, I ride them because they are insanely light.