I have quite a bit of experience in storing hops and dried foods in mylar bags! You have to watch to not fold mylar bags more than once as otherwise you'll start to get pin-hole tears in them. This can be a real problem when you're talking long-term. I mainly buy bundles like http://www.mylarshop.com/mylar-bag-oxygen-absorber-bundles Another thing you have to watch out for is when you're buying oxy absorbers you're going to need some way to reseal them as, if left open to the air, they're going to run out quickly!