For the 2019 iPad Air, Apple's Smart Keyboard is essentially a MacBook keyboard build into a Smart Cover, allowing it to serve as a cover for the display, a stand, and a physical keyboard. With keys covered in woven fabric, the Smart Keyboard is resistant to water and other liquids.
Measuring in at 4mm, the Smart Keyboard does not include wires or standard keyboard components so it does not need to be charged. Instead, it attaches magnetically to and is powered by the Smart Connector along the side of the iPad. The Smart Keyboard for the 10.5-inch iPad Air is priced at $159.
For the 2018 and 2020 iPad Pro models, Apple offers a Smart Keyboard Folio that is nearly identical to the Smart Keyboard but also includes a panel that protects the rear of the iPad Pro. The Smart Keyboard Folio is priced at $179 for the 11-inch model and $199 for the 12.9-inch model.