Amazon's weights are generally in-package weights, not the actual product. It definitely doesn't feel much different weight-wise and I saw the 710 grams here -
https://www.makeuseof.com/reasons-ipad-magic-keyboard-isnt-for-everyone/
https://www.creativebloq.com/reviews/magic-keyboard-for-ipad
https://mashable.com/article/ipad-pro-12-9-magic-keyboard-heavy
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