These surpassed my expectation! I have since used most of the bags (in 3 different sizes) and all have held their seal really really well. Only one re-inflated ever so slightly but not enough to make me want to unpack and return the product. The hand pump it came with actually works really well - you have to screw the pump in and pull/push to 'extract' the air. I also tried with a good vacuum and I found the hand pump was actually more effective, which is handy, especially if you were to take the bags travelling etc.