The body is built with 304 grade 18/8 stainless steel inside and out. We wanted to make a life-proof product that could withstand the regular drops and bumps you'd expect during daily life.
The space-grade material has been tested extensively and showed no significant loss of performance after 6000x cycles. For the average coffee drinker (at 3.2 cups per day,) that's over 5 years of perfect coffee!
As for the lid, we are still in the process of figuring out a win-win lid replacement policy. But until we figure that out, we'll do our best to replace any broken lids so that you can continue using your ThermX!