These are quality inexpensive tubes. The valve stem is threaded all the way to the base and there is a nut that goes over the threads. This gives you the ability to secure the valve stem in place making installation incredibly easy.
Normally have great luck out of continental tires and tubes. But the first tube I had blew up while inflating at just over 40 psi. Had to run to the local bike store and pay twice the price for a lower quality tube. Kind of disappointing, but the other three held.