Where's the next/previous-page button for custom toolbar?

Under Navigation (F5) > Page there’s a function for going to the next or previous page. See screenshot. This option is different than PageDown and -Up and works better.

How can i get this function on my toolbar? I can’t find it in the customisation menu for toolbars.

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I see it in “All Categories” and in “Navigate” as “To Begin Of Next Page”/“To Begin Of Previous Page” (at least in 5.3.0.3).

Not the same effect here.