The MM350 arrives rolled up in a box, which follows the color scheme and style of the new Corsair mice with a lot of bright yellow and black. Once opened, you can access the mouse pad and two small warranty booklets. The pad can be quite smelly at first, but this is normal, and the odor should completely disappear within a few days. The mouse pad of course doesn't lay out completely flat right out of the box as it needs some time to flatten out completely, but it doesn't remain wrinkly at all. As a matter of fact, I could use the pad right away without any issues.
Size and Surface
There are two main size variants of the MM350, an XL version of 450 mm x 400 mm x 5 mm (7.7" x 15.7" x 0.2") and an extended one of 930 mm x 400 mm x 5 mm (36.6" x 15.7" x 0.2"). The mouse pads are rather thick, so expect a hefty weight to them. I'm not sure if they'll plan to reveal more sizes in the future, but I guess the smaller variants could use some extra padding as well.
The MM350's surface is extremely smooth and silky, very similar to the SteelSeries QcK Limited, but this one's ever so slightly rougher. The mouse really flies across it with very little resistance, however, and I've found it to have a bit less stopping power than the previously mentioned Limited. Mouse pad surfaces are up to personal taste as some love smooth ones like this, while others prefer slightly rougher materials, so while this one is really silky that doesn't mean it will naturally be better than the competition for every single user.
As for the underside, it's a quite standard rubberized material with the usual diagonal waving pattern. It's not the best backing I've tried, but with this weight and thickness to the pads, it does the job well. I had no issues with slipping whatsoever. In my opinion, without the wavy texturing, it could have better tackiness with the table as this way, there's less material touching, which reduces the friction between table and pad significantly—while I might be wrong, I am basing this on my own personal experience.