Tossed my 22oz in a backpack sideways on a hike and not a single drop leaked out. The twist-on seal is genuinely tight, though you do have to make sure it clicks fully or it won't sit flush.
Evelyn V.★★★★★
Wasn't sure a lid could make much difference, but this one twists on so tight I don't think twice about laying the bottle sideways in my bag. No drips at all, and it's a simple twist to seal.
Richard★★★★★
Tossed it in my bag upside down on the way to work and not a single drop escaped — the twist seal really does lock tight. Fits my 22oz like it was made for it, which I guess it was.