I've been using plastic protein shakers pretty much daily for years and finally got tired of using plastic. I found a brand that makes glass shakers with glass lids, but the seals on the lids are hard to clean and get moldy. So, I looked for a solution, and these lids have been awesome! I get questions all the time at the gym about these. If the lid is on correctly, I can shake it pretty hard with no leak, I can carry it upside down with no leak, etc. I will note that the silicon mouthpiece and the metal rim are two separate pieces, so you do need to make sure you have a good seal when you screw it on. I've also used it in the sauna. Great product!

This works perfectly for mixing shakes in the jar, easy to clean, no leaking!

These seem like they will last a good while!

I have used mason jars for everything for many years. I am not an internet surfer thus only recently found the tools I have been dreaming about!!!

They have all of the things I imagined, made better than I imagined!!

Thank you so much! Verna ;)

These are great,they dont leak&easy to drink from