Review on Continental Bicycle Tubes Race 28 700x20-25 S42 Presta Valve 42mm Bike Tube Super Value Bundle - Pack of 5 Conti Tubes & 2 Conti Tire Levers for Optimal Performance by Shane Minter

I don't know if these are cheap Chinese fakes, or if they're just pipes that didn't pass Conti QC, or if they've been in storage somewhere for the last ten years, but these pipes are complete rubbish. If you inflate them without installing them, you'll see bulges and bumps where tube wall thickness varies greatly. If you install them, you will find, like me, that you need to use 4 tubes to go 6 miles. That's right, it took me 2 hours to get 6 miles today because every tube I put in my Conti Gatorskin tires had a hole small enough to hold air and then over the course of a half mile to drain fast. It took me 4 tires before fitting one that didn't flat tire and was able to take the bike home. 2 holes were in the valve stem seat and the third was in the tube. The tubes were installed correctly and my rim and tire were checked for dirt every time. I wasted my trip, 2 hours and $30 for this junk. Do yourself a favor and avoid them and just buy some good whistles at your local store.