I've finished DD1's second nursing t shirt. I used 2 visible zips from stash and had no end of trouble. Cut to length, flamed the ends, overstitched. The first one went in fine but the second side of the other zip was unpicked 4 (yes, four) times before it was acceptable. I think this was because the zips were too thick. The invisible ones I've lost (obviously completely invisible) had much smaller pulls & thin tapes. On the plus side, I found a tube of toothpaste in a rather strange place. Yes, I searched our bedroom & the bathroom for the hidden zips & still didn't find them.