I tried this for the first time two weeks ago with a 19 lb. bone-in ribeye purchased at Restaurant Depot. I had an awful time getting a good seal on it and used all three bags. That being said, the third and final bag did have some air in it, but it adhered to a good portion of the meat. I was so upset over how difficult it was that I reached out to UMAI about my experience. They assured me that a little air in the bag was not an issue as long as the meat was adhering. They also kindly replaced my bags for me. I am now two weeks in, and the meat is looking great. It has changed to a very dark red and looks to be heading towards the dark brown bark. I plan on letting it go for a total of 28-35 days depending on how it looks.