I got a very small leak on a bicycle tube.  Too small to see, but could feel the air.  I followed the directions exactly, then slowly pumped up the tube.  It was flat by the next day.  I removed the patch, then repeated the repair.  This time, I used a rubber roller to firmly press the patch to the tube.  Same results - in less than 24 hours, the tube was deflated.  Do not waste your money or time with this kit.