I freaked out when I first received this because, while checking out the product, I pulled off the black plastic cap before discovering that it says "Do Not Move" on there. I had to do some research to discover that this is the vacuum valve cap and, as long as I didn't somehow release the vacuum, everything should be fine. There is a layer of vacuum grease around the valve that should not be disturbed. If you're interested in the process of evacuating a dewar, there are a few videos online that you can search for.Okay, now onto the review of the dewar itself. It's really well made. Quality from top to bottom. Comes with a nice cover that doubles as a carrying bag. There's a flip top lid that snaps shut. Obviously it doesn't shut airtight or it could explode, but there's a satisfying click when it's fully closed.Under the lid, there is a foam plug. Remove the plug to reveal three canisters for lowering items into the liquid N2.I was able to get mine filled at the local (welding) gas supply shop. Surprisingly cheap, I though it would cost more. I then proceeded to do the typical experiments for my kids like shattering a flower in my fist and frozen marshmallow dragon breath.Truth be told, I don't really have much of a reason to use liquid nitrogen at the moment (other than just geeking out). I'll be going back for a refill soon to try making ice cream with it, but that's just another fun, nerdy experiment. Perhaps someday I'll have an actual good reason to use liquid nitrogen, but for now it's all just for fun.Great little dewar. 3 liter capacity is certainly not very much, but if you need something larger, this company does sell some higher capacity models as well.