This would be a good replacement zipper for jackets, ski coats, kids items. Easily shortened from the top for your project.
If you need to shorten this zipper, add 2 top stops to your order per zipper. The top stops keep the pull from running off the top of your zipper.
The #7 means that the closed coil is 7mm across. So a #3 would be 3mm across & is a standard dress weight zipper. Or a #5 would be 5mm across which is used in ski jackets, hoodies, dog beds, upholstery & cushions because of it's strength. #7 are just a little heavier.
FYI: #7's are sometimes a #5, depending on the manufacturer. #3 Coil is pretty standardized, except Coat & Clark zippers. #5's seem to be all over the map. YKK calls all their zippers #5 but it depends on the plant they are made in! This only matters because sometimes the zipper heads won't fit or they run tight.