A few months back, ASUS announced its ZenFone 3 range. It's a collection of several devices, with specs ranging from affordable to high-end devices such as the ZenFone 3 Deluxe and the ZenFone 3 Ultra. The ZenFone 3 Max is at the bottom end of this spectrum. With this phone, the focus on features and performance has been dialed down in favor of battery life. Like the previous phone in the Max series, the ZenFone 3 Max features a massive battery pack designed to get through an entire day of intensive use or even two.
Source: http://www.gsmarena.com/asus_zenfone_3_max_zc553kl-review-1548.php