The rear latch is one of the more popular types of magazine retention as well as a release mechanism. It is basic in its design and offers users having access to the release on both sides of the gun. To enhance your knowledge of this, you can also check about magazine release button online.

Different types of magazine release buttons of guns.

Type 1: Side Latch (Lever Type) Right-Hand Biased Spring driven fixed pivotal lever that comes with teeth that engage and is locked into a slot inserted in the magazine. This mechanism is advantageous because it has the benefit of being accessible via your trigger finger on the hand that is firing when it is placed on your pistol's grip. 

Type 2: Transversely operated side latch, push Button (Right hand biased) – This design is found for models like the M16A2, M4 Carbine, FNC, and various other weapons which use the NATO 5.56 30 round magazine (M16 Type). As with Type 2, it is accessible through your trigger finger right-handed shooter, with the firing hand positioned within the grip of the pistol. It is a similar issue to Type 2 as the button that triggers the gun is located on the right-hand side of the gun.

Type 3: Improved transversely operable side Latch and Ambidextrous ReleaseThis model combines the top features of several release models, providing the user with the most diverse choices for magazines release.