Failed within 24 hours on 45mm tires. Postmortem showed failure at the nonelastic reinforcement opposite the valve. This area will not stretch when fully inflated, leaving two sharp wear points. These are probably good up to about 38mm tires.
Well made tube! The valve I really like, because my previous purchase from another company the valve threading doesn't even let the cap go fully on before the rubber tubing stops the cap. Compared to the valve your tub has. It goes all the way to the rim and is made out of a rust proof material it seems. Throughly enjoy my purchase.
I had four flats within two weeks against the inside of the rim with brand K. I ordered a couple of these Continental Tours and a couple of Michelin Airstops to see if it was the fault of my rimrim tape (I never could find any problem with the rim or tape) or if it was the fault of the tube. I put in the Continental and it has been over 30 days and 400 miles of riding and I haven't had a flat (so I haven't tried the Airstop yet). The overall quality of the butyl, the seams, and the valve look better than brand K also.
Installed the tube on new tires purchased at the same time. If you need a refresher on how to install tubes, read the instructions on the website before you damage the tube. I have had the tubes in for over 2 months now and have not need to add air. My tire are 700c x 42mm. I have put on about 100 miles, so not very much. Tube is holding up well and I like the metal stem.