Samsung Galaxy S II was launched in April, and in July Samsung announced it sold 5 million units; reaching the 10 million milestone in such a short time span is quite an achievement, given the device only became available in the US a couple of weeks ago. 

However, one must take into account that Samsung is talking about channel sales, which is a bit different from end user sales. Still, hitting 10 million in only 5 months is a noteworthy achievement for any smartphone - except one, and that one starts with an "i".

The specifications for the device differ slightly in the US, depending on the carrier, but it's a very powerful smartphone regardless of the variety, with a dual-core 1.2 GHz Exynos CPU, Android 2.3 Gingerbread, 1 GB of RAM, an 8-megapixel camera and 16 GB of storage.