This is the Glock 43 6 round magazine from the Glock factory...just like the mag that came with your gun.
There are probably a few accessories you'll want for your new Glock 43...some extra G43 magazines is most likely first on your list. You can shoot through six well placed rounds in under 3 seconds and then...reload time
Luckily you're only going to be reloading 6 rounds so it's fairly quick, but that's why you're on this page...you want a few extra magazines already loaded so you can keep shooting.