I noticed that some of these reviews were several years old. I bought 2 of these a couple of months ago (Feb 2015) when I upgraded my system to 15 gal. I like to brew lagers so I need big starters. I have made 3 starters in each of these with a glass top stove. I have no problems boiling, moving straight to cooling water, and using my stir plates with these. I would recommend these to anyone that needs large starters and has a glass top stove.

For lagers I need extra large starters. The flask is big enough to hold 4 liters and still have some head space to avoid a boil over. It fits on my Vortex stirplate, and meets my expectations.

It's just what I need for making very large starters for lagers or 10 gallon batches._x000D_I boil on a gas stove, then set it on a mat to cool for a spell, then place it in a sink of water to chill._x000D_I place it off center on my stir plate so the center isn't a problem.

The bottom has a bump so the stir bar will get thrown if centered. Its also not as thick as I'd like and it can break if you're not careful.

I need to make a lot of yeast for a 10 gallon lager and this flask is the only thing big enough. I boiled 5 liters of water in a pot, let it cool down in the sink, then poured it into the flask and added the stir bar and set it on the stir plate at high speed. I let it go for 1 week, then refrigerated it and decanted off 4 liters of spent wort, and pitched the last liter. I'd have preferred to prepare the starter inside the flask, but I was concerned it would crack on my gas stove.