Lenovo Zuk Z1 is powered by the Qualcomm Snapdragon 801 CPU with 3GB RAM and 64GB of ROM. The LCD IPS display is 1080p at 5.5″ and has a contrast ration of 1500:1. The Sony camera sensor, which has an f/2.2 aperture, takes 13MP and has optical image stabilization. It has a large 4,100mAh which supports fast-charging via its USB Type-C plug.
Lenovo has promised Marshmallow update for Zuk Z1 but it has not received Marshmallow as of now. You can always use custom ROMs if you want to update Zuk Z1 to latest Android version. An official nightly of CM 13 ROM running on Android 6.0.1 is available for Zuk Z1. If you want to install it, follow the guide below.