I bought these for my daughter's second baby to replace the ones she had for her first wee boy. She is delighted with them but a bit disappointed with her original ones in which the zip broke on each. It was the 'pull' bit which needs to be very robust when trying to hang on to a wriggling baby at the same time. This didn't stop her wanting exact replacements but it seems a small thing to render the bags unusable. So strong zips with really perhaps larger 'pull' bits would help save binning otherwise perfectly good bags and make them more sustainable.