This is worded rather strangely so it might be a typo, otherwise is seems Apple has gone back to a 10W power adaptor on the iPad Air 2 and even the first Air. But oddly you can buy a 12W separately. Cost savings seems inconsequential so I wonder why.
From the FAQ at the bottom of http://store.apple.com/us/buy-ipad/ipad-air-2
From the FAQ at the bottom of http://store.apple.com/us/buy-ipad/ipad-air-2
Which power adapter should I use to charge my iPad?
iPad Air 2 and iPad Air come with a 10W USB Power Adapter. iPad mini 3 and iPad mini 2 come with a 10W USB Power Adapter. iPad mini comes with a 5W USB Power Adapter. If you need to purchase an additional adapter, choose the 12W adapter because it can charge all iPad models.