Although the previous reviewer states alumnium .. directly from the website:
"Originally designed by SIGG in 1941 for the Swiss Army,
the sleek and stylish Oval Bottles make their triumphant return.
These hip new flasks are made of stainless steel and perfect for any
beverage. This sylish red flask is perfect for camp, and is made with the
same high quality you've come to expect from SIGG. Drink knowing our
eco-friendly flasks will NOT change the purity of your beverage inside.
"

This item couldnt be any better. And it is stainless steel 5 stars

This product has changed in its design recently. The shape has harder edges and less gradual sloping, but is not as angular as the one in the picture. I guess they have not updated the picture.

The label on the box of the new version has a sticker saying it is lighter. In any case, the aluminum casing makes this item very light.

The inside enamel coating is also paler, more like yellow now and has no metallic smell or taste. I mean that when you put your tongue up against it, you cannot 'taste' metal the way you can with other containers or, for example, soda cans. Sometimes, the enamel coating is not evenly applied or sometimes has rust spots near the lip. This happened on one which I returned.

The hole-in-middle cap is also great. Made of two plastics, one harder material for the base and a layer that is slightly softer so that it has a 'give' and can create an airtight seal with the container body.

external paint job is high quality, glossy surface. 5 stars

*****
This is an upscale designer water bottle, top of the line in every way. The designs of Sigg's water bottles are gorgeous, from the plain, solid color bottles (like this one), to others with intricate designs. The oval design makes this bottle different from most others, too, giving it a distinctive look.

I switched from regular plastic water bottles because of health concerns, even though I thought a permanent bottle like this would take more work to maintain. These do necessitate regular cleaning (I clean mine every day), but having something so beautiful to drink from makes the cleaning less of a chore. Sort of like my rings, glasses, and watch, I now consider my Sigg personal water bottle a vital accessory, reminding me to drink more water, making a statement about my values, and expressing myself with a special design.

Sigg of Switzerland water bottles are very high quality, made of light aluminum on the outside, slightly insulated, and covered with a special powder coat on the inside that prevents any leaching whatsoever, unlike plastic and polycarbonate water bottles. They are light, durable, and perfect for any activity. Well water tastes spectacular in these bottles, just like from the tap. They do dent if dropped on a hard surface at a particular angle, but Sigg fans (including me) view this as a type of "seasoning", so that your bottle acquires character. The dents are on the outside layer of the bottle, not the inside layer and so don't interfere with any functionality.

Sigg bottles come with several different types of tops. This bottle has a screw top, which I prefer. I don't mind unscrewing the top when I want a drink. It is totally leak proof, which is important to me. The top is pretty and can be hooked onto a carabineer. If you ever lose the top, you can buy them separately.

Sigg makes their personal water bottle in many sizes. I use the .6L size as my basic every day size, and keep it in my briefcase. It is a bit too large for my purse, although if you carry a tote it is an ideal size. It is also good for sports activities that require less water, like shorter walks. For my car and other uses I use the larger 1L size.

This bottle may seem expensive, but it is so durable that you can plan on it lasting many years. I consider Sigg bottles both an accessory and an investment in my health, so they are well worth it value-wise for me.

Note that Sigg water bottles should not be used to contain boiling water, as this will damage the outer coating. They also cannot be left in the freezer, as it may crack. They can be used for carbonated beverages, if you leave about a half inch of room at the top.

Highly recommended.
***** 5 stars

Excellent water bottle, great size/shape, sturdy, a little difficult to clean the inside, but not a major issue. Plastic is dead; go aluminum! 4 stars

While the 1941 Swiss Army canteen reproduction flask from SIGG with the cup is stainless steel, this model no longer is. The box describes it as "NEW & LIGHT", made of "lightweight metal" rather than stainless. I own both versions, and the stainless bottle is 30% heavier, has a matte powder finish, while this has a clear-coat finish identical to my other SIGG aluminum bottles. I believe their website is out of date, and the reason they do not claim the entire bottle is aluminum on the box is because the threaded neck piece that the cap screws into is still stainless. The all-aluminum bottles have coating over the threads, this one is coated only inside the bottle, while the threads are bright.

Also note that the cylindrical, all-aluminum SIGG bottles are made in Switzerland, while all the flasks - both stainless and aluminum - are made in China. 4 stars