 Asus designed the Zenbooks with brushed aluminium chassis and high rigidity , rather than plastic , the usual laptop construction material . A pattern of concentric circles on the lids is said to represent ripples in water and represent the " zen philosophy " that designers wanted to portray when creating the laptops . Zenbooks have been generally well received due to their chassis design and appearance as well as the high quality screens used in later models . However , the touchpad software was found to be erratic , particularly on the early models and some of the models received criticism for their high prices . Some models ( such as the UX32 ) suffer from lockdown when the lithium polymer battery cell gets drained or discharged below its recommended threshold , for example if the device is left on and unattended . The result is that the charger will fail to recharge the battery even when plugged in , leaving the machine in a near @-@ complete unresponsive off @-@ state . The machine can often be revived by pressing the power @-@ on key for 10 seconds , whereupon it will start recharging . 
