Asus Zenfone Max Pro (M2) ZB631KL official Pictures. Asus Zenfone Max Pro (M2) ZB631KL is a Smartphone of asus. The Asus Zenfone Max Pro (M2) ZB631KL Android Smartphone. Announced Dec 2018. Features 6.26″ Display Snapdragon 660 Chipset 5000 MAh Battery 128 GB Storage 6 GB RAM Corning Gorilla Glass 6. Asus Zenfone Max Pro (M2) ZB631KL price starts.