ZE551ML variant of the ZenFone 2, which has the most high-end components of the lineup. The phone has 4GB of RAM, which is the first for any smartphone we've reviewed. It also has a 2.3GHz quad-core Intel Atom Z3580 processor with an integrated PowerVR G6430 GPU. Incidentally, the same graphics chip is also used in the iPhone 5s. The phone has 32GB of internal storage space and there is a microSD card slot which can be used to add 64GB more space. Furthermore, the Micro-USB port can be used to plug external USB drives in.The phone accepts two Micro-SIM cards. The primary SIM card can connect to 4G networks including the 2300MHz Indian 4G frequency band. Both SIM cards can connect to 3G networks. Other connectivity options include Bluetooth v4.0, Wi-Fi a/b/g/n/ac and NFC. The ZenFone 2 has a 13-megapixel primary camera with dual-LED flash and a 5-megapixel front-facing secondary camera. The phone also has a fairly large 3000mAh battery under the hood.The 5.5-inch IPS LCD screen has a resolution of 1080x1920, which translates to a pixel density of 403ppi. Images look crisp and the colours are also accurately reproduced. Even the viewing angles are pretty good. The only weakness of this screen is that even at maximum brightness it looks a bit dull, which in turn affects the sunlight legibility.