Each GLOCK magazine is constructed from a hardened steel insert encased in high tech polymer to protect the magazine and prevent deformation, even when dropped from a great height. The high quality spring and follower ensure reliable feeding from the first round fed by a fully compressed spring down to the last shot. Its double cut magazine body also works with a reversed magazine catch on Gen 4 and Gen 5 GLOCK pistol models.
Needed an extra mag, great price, and it shipped fast. No fancy packaging but authentic. Added a plus 1 extension and no issues during my range trip.