It Leaks
I don't know if the rubber seal was properly installed or not, but it definitely leaks. The metal on metal threads grate on each other and don't seal very well. Plus, if you're the kind of person that gets the heebie-jeebies from metal scraping on metal, don't purchase this water bottle. Also, the top is kind of hard to unscrew. If you put your finger through the hole to get more leverage, it kind of wrenches it.

great bottle but ...
I really like this bottle and I bought two because I always like to make my teas in bulk. Today, I dropped one for the first time and cracked the plastic off the closure/plug. I was unhappy that the fall broke the cap, but the seal is still intact and the cap that's left can still operate, so it's not a total loss by any means. Still, I'm buying the blue stainless cap and I'm getting the Sport's Cap for this size as well. I wish there were flat topped caps available for the New Wave Bottles, the way there are for other peoples' bottles. (Hint! Hint!) Nontheless, this was a good deal for my money as well as for the environment and I'd buy a third one if something dire happened to one of the 2 I have.

Enviro 40 oz steel water bottle
This is a well made canteen. I particularly like the steel stopper, as I've seen these bottles with plastic stoppers. I drink my lemonade from this bottle confident that no one is going to tell me that I've been poisoned by it like my experience with the lexan bottles.

New Wave Enviro Stainless Steel Water Bottle
These work very well for water and other liquids. Bought them for my husband and he really likes them.

Great Product
I first decided to get this water bottle when I heard the concerns with some of the plastics used in others. I figured as much as I was drinking out of my last bottle, might as well be safe and get one of these. Here are the
pros:
-As I mentioned, it's metal
-The metal doesn't pick up funny odors or tastes as my plastic bottle did
-Seals well and doesn't leak (as long as you turn it all the way shut)
-Holds plenty of water (40 oz.)
-Easy to clean, just put some vinegar or baking soda in it, there aren't any crevices that are difficult to clean either!
cons:
-Bulky (well obviously because it holds 40 oz., hardly any wasted space)
-Dents easily (doesn't affect its function, only its looks)
Well the cons don't bother me and I have found this product to be extremely useful.