This product is awesome! It works as all other bicycle tubes do. Rolls or folds up small enough you and can fit 2 of them in a saddle bag underneath the saddle. It fits the tire and rim size that it states on the box, amazing, and when inflated it holds the required air pressure. Just like every other tube on the market, this miracle product allows me to pick the tire pressure I want and holds it for weeks before it.
My BMW eBike came equipped with 28 Rodi Airline Plus Rims with Schroeder valves. The 29 Kenda tubes I purchased came with a standard length valve stem. I learned my Airline rims rims require a 14 (6.35mm) longer valve stem. so I can use my air compressor to air up my tires. Other than the length issue the tubes fit very well. I would recommend the Kenda Brand.
I only recently installed this tube. From the looks of it it appears to be a quality made tube and is made in Taiwan. The tube also seems lighter than the stock Kenda one made in China.. However I can not tell a difference while riding. I have run many different brands of tubes on my bikes and I honestly don't see a measurable difference with my type of riding. No significant air loss while bike is laid up. I rode some pretty knarly single track recently with roots,brush and rocks etc and they held up fine. That's all I have and I hope to get high mileage from them.
I've been using only Kenda tubes for my road bikes for years and just bought these for my new 29er. If installed correctly, they'll last for...ever. On the road bikes, I pair Kenda tubes with Specialized Armadillos. These are just backup and the stock tires on the 29er have to puncture protection so we'll see what happens.