I love my Swig tumbler that I've had for...two years maybe? Until recently, the regular lid that came with it was good enough. It didn't stop leaks if the bottle got tipped, but the bottle didn't get tipped often. Enter toddler. My baby loves my tumbler and as soon as he was big enough to reach it and grab it, it's been non-stop spills. So I ordered the leakproof lid and I am super happy with it. It really is leak proof so far as I have seen after using it for a bit.
Now can we please please get the leak-proof to go lid (with the top handle) for 40 oz Swigs!?!?