4g smartphone phablet android phone dual sim phone series zte axon display size 55 inch display resolution 2560 x 1440 pixels display resolution quad hd display type amoled touchscreen multitouch capacitive display characteristics 25d glass display display properties scratch resistant display material gorilla glass 4 pixel density 538 ppi brightness 357 cdm ram 4 gb internal memory gb 64 gb usable internal memory 52 gb max memory expansion