Bests & Worsts Reviews from Amazon

If you look inside the cap on this mug you'll see what holds the white (removable) piece in place. It's a tiny piece of plastic about 1/8" wide by 1/6" tall. That's it. It will break on you, and after talking with the company, you're out of luck. The replacement part is over HALF the total cost of the mug. Be prepared to invest more in this product than advertised.