At first, I was going to give this item 4 stars as these vacuum bags do feel like really good quality (up to the same standard as my expensive vacuum bags), but that star rating started to fall after I started using them.
The clips that come with the bags are for sealing them shut, but because the clip is way too loose, you need to squeeze is hard while at the same time pulling it across, which is a pain. My expensive vacuum bags are tight enough to seal without pressing down hard and they also stay on, unlike these ones which fall off after you've sealed the bags and then you'll probably end up losing the clips. Although you can clip it shut yourself but it would take a while, hence why they come with the clips in the first place.
And now to the reason why I've given 1 star...they just don't work. I have more expensive vacuum bags (£20 for 4) and they actually do work. When you're using the vacuum on these bags you're supposed to stop and think "oh wow that's amazing" not "oh, is that it", because that's how I felt with these. They do take the air out but just not enough, which I don't see how is possible but it's probably due to the bad valve. The description says it reduced the volume by up to 80%, they've said "up to" because it's probably around 20%.
I simply cannot give any more than 1 star as they don't work to nearly the same standard as others I've tried. They don't take away enough air and they simply aren't as good as the listing images show (which by the way are hilarious). You'll know when you have good vacuum bags because you won't be able to move the items around while feeling the bag, it will literally turn your items into a solid brick, and honestly, you'll just KNOW they're good. These aren't.
I didn't get the set with the pump but I can assure you a pump will NOT work with these bags. They're called vacuum bags for a reason, you need a vacuum.