I don’t do inventory like this frequently, I am too lazy. I only recently learned about Mylar so this is the first time I use it, and I wish I started using it years ago. Especially for my bulk blends. I have a ton of large jars filled that are heavy and bulky. It would have been way better to use mylar instead. Now I don’t want to open them and move the contents to mylar because it will interrupt the aging process but as I open large jars to add a portion to my rotation jars I will be moving then over to mylar. These vacuum type tins are definitely not air tight because there was a massive aroma from every storage bin I opened.. If I can smell the tobacco then air is getting out.