iPad Air compatibility

Magic Keyboard? Which one, as there are several that carry this “generic” name? 

The Magic Keyboard for iPad can be used with the third and fourth generation iPad Pro 12.9”, the first and second generation iPad Pro 11” - and the fourth generation iPad Air. This Magic Keyboard is designed explicitly for these models - and cannot be used with anything else.

More details can be found here:

https://www.apple.com/uk/shop/product/MXQT2B/A/magic-keyboard-for-ipad-air-4th-generation-and-ipad-pro-11-inch-2nd-generation-british-english

The standalone Bluetooth Magic Keyboards for Mac can be used with most models of iPad.

https://www.apple.com/uk/shop/product/MLA22B/A/magic-keyboard-british-english

Additional compatibility information can be accessed here:

Apple Wireless Keyboard and Magic Keyboard compatibility with iOS devices - Apple Support

Yes. Magic Keyboard is compatible with iPad Air (4th Generation).