A base pad adds weight at the bottom of the G43 magazine so it exits the grip cleanly on release -- on a single-stack slim-line magazine where the lighter weight of a narrow magazine can slow the exit under some conditions. The G43 is Glock's slim 9mm subcompact and its magazine is a different format from the full-size and compact Glock double-stack designs -- base pads for the G43 are specific to the slim-line magazine.
Confirm compatibility on the individual product page before ordering.