Genuine factory magazine. The GLOCK G44 Compact Frame magazine has a hardened steel insert encased in the proven Glock high-tech polymer. This resists deformation - even when dropped from great height or exposed to extreme environment conditions. The magazine has a window for each cartridge so there is no question how many rounds are loaded. The high quality spring and follower ensure reliable feeding from the first to the last shot.

Note from manufacturer:
Glock magazines have very stiff springs when new and may be extremely difficult to load to full capacity. It may be necessary to use a Glock magazine loader (generally included in the Glock case with the handgun) to load the magazine to capacity or near capacity. If the last round appears impossible to load, for example if the magazine should hold 15 rounds and it will only accept 14, leave it loaded with 14 rounds for several days to allow the spring's tension to decrease. After a short time, the magazine should then accept its full capacity, but it may still be necessary to use the magazine loader. After several cycles of full capacity through empty, the magazine will be easier to load.