Stat of the day: around 30% of Apple's iPad profit comes from selling smart covers.
Richard Kramer, managing partner of London-based Arete Research, calls it the 'after hardware' market - making money from accessories.
The covers "cost $5 to make, and Apple sells them for $39."
"They sell 15m iPad units, 90% are smart cover-attached, that's $450-$500 million in profit they made for selling accessories for a device."