This lid fits on standard wide-mouth nalgene bottles. Also fits my camelbak * mag vacuum 40 oz bottle. Spout is just the right size - small enough to cover completely with my mouth.

Make sure to pop out the silicone part in the lid (gently wiggle out) with a spoon. Easy to pop open. It clicks into place, but also has an extra metal piece to lock it down. Metal bar to keep it from accidentally popping open.

Lid is flimsy and doesn't latch properly. Lid leaks from where it twists onto the bottle. If you screw the lid on tightly, so it doesn't leak, it is difficult to unscrew without putting pressure on the top part.

Lid of nalgene water bottle has serious molding problem on the silicone inside. Water gets trapped underneath the silicone itself with no way to access it unless you remove the whole silicone portion, which would destroy the lid.

There's never a time for them to regularly sit idly. Do not but this lid.