Review on 16 OZ Protein Workout Shaker Bottle with Mixer Ball and 2 attached Storage Jars for Pills, Snacks, Coffee, Tea. 100% BPA-Free, Non Toxic and Leak Proof Sports Bottle by Melissa Davis

I was a bit concerned when it kept leaking when I closed the lid and shook it. There is no rubber seal where the top of the bottle meets the inside of the cap when fully closed. I had a cover on the right side but it kept going. I had a thought and after putting the lid on I opened the part you drink from to let out any air that might have been there after I put the lid on, closed it again and then shook it and it didn't run . . I've tried a few more times and each time it hasn't leaked, so I think the pressurization is pushing air out of the part that really should have a rubber seal. Also, I'm disappointed that I can't stick anything on the outside of the bottle or jars. I wanted to mark them, but nothing sticks.