According to Apple’s website, “The Smart Keyboard is a full‑size keyboard made for iPad. It delivers a comfortable typing experience wherever you are and converts into a slim, durable front cover when you’re on the go.”
This keyboard uses Apple’s proprietary Smart connector so the keyboard does not require its own power. “Just attach the full-size Smart Keyboard to your iPad and start typing — no charging or pairing required. And when you’re finished, it folds up to become a slim, lightweight cover.”
The iPad Smart Keyboard is Apple’s first case-integrated keyboard for the base-model iPad. It is compatible with iPad (Generation 7 and 8), iPad Air (Generation 3), and iPad Pro 10.5‑inch.
Source: Apple (iPad Keyboards, iPad)