I love my tea balls. I use the giant one for a single large hop addition (when I bittered my märzen with 3.2% AA Tettnanger, or when I put 4-6 oz of pellet hops in at 5 min for an IPA). I use a 3-inch one for keg hopping and for moderate hop additions in the boil. I use little ones (2") for keg hopping and for small additions. Since I mostly use whole hops, I only need the balls or hop bags when I am using more than about 1.5 ounces of pellet hops. When that does happen, I have had absolutely no problems with the stainless hop balls. the large one would be impossible to open mid-boil to add hops to since the hops expand to fill the ball no matter how many hops I put in it. I have not had a problem with AA extraction - it has always been roughly the same as when using a nylon "hop bag" or a cheesecloth peasant's purse.