是这个(nano-SIM card).
Do all iPad models use the same type of SIM card?
No. iPad Air, iPad mini with Retina display, and iPad mini all use a nano-
SIM card. All other iPad models use a micro-SIM card. Micro-SIM cards cannot
be used in devices that use nano-SIM cards.
From FAQ: http://store.apple.com/us/buy-ipad/ipad-air