I am not familiar with that brand but I do use something that looks similar (that I buy at Wal-Mart). The key is making sure it has a silicone, and not a rubber, gasket, as the rubber ones will degrade with time. I personally only use them to store my open tins in and also my esoterica 8 oz bags, but I know others who use them for flakes or loose tobacco with no issues. My personal choice is that I use mason jars for flakes or loose tobacco, however, and I am even so anal that I dip them in hot wax until just past the lid line just in case, and I do the same with my Wal-Mart bale jars (not the ones holding open tins - but the ones holding esoterica bags). That said, when I bought my bale jars I did a test - filled one up with water and shook it violently and left it hanging upside down all night - not a drop escaped, so I think they can be pretty airtight but be cautious. I do trust them enough as a backup to unopened esoterica bags.
Edit: Clarified