QTubes are junk. High failure rate and they don't hold air very well. I bought 4 of them somewhere and after my experience with the first two, I threw the other two away. Mostly I stick to Continental or Schwalbe tubes now and I can't remember the last time I had a problem with a tube. Not having to inflate my tires each and every time I ride is a big plus for me. You get what you pay for.