OK, I'll volunteer to ask the dumb question:- If sealing the plastic bag with a zipper (where a ridge is pressed between two others and has been the standard way of sealing plastic bags for two decades or more) HOW do they want the bag sealed?
Since they state "Able to close properly with all the items inside...." are they happy with a twist closure? ANY method of sealing a plastic bag will expel air. Since you are standing over it, any malign substance would affect you as well.
Sheesh.