Sumsung galaxy s 2 duos is Android operating mobile.In this mobile 4.2.2 Android version is running which is Jelly Bean.It has built-in 4gb rom and It have nice quality back and front camera.Front camera 2.0MP Back camera5.0MP It have 768 MB ram which is good enough.It have 1500 mah battery which is good enough for normal uers.It is easily protable in your pocket. It looks is very nice.It mobile hae good featues. I recommended it for normal users who want to buy a good and nice features quality mobile. I rate 3 stars this mobile because it is best for average users and normal users.