in fact sterling had a theory he had a theory about a lot of things that holding the iphone was a very good substitute for holding ones other thing ; granted the former was shorter ( 4.5 in , but small is good for hand-helds ) and heavier ( 4.8 oz ) , but it had a lot more useful functions and time-wise ( 5 hours of continuous activity , a whopping 300 hours on standby ) ; there was simply no comparison .