These are factory original drop-free magazines for your factory Glock handgun. Factory Glock magazines have a hardened steel insert encased in high tech polymer. This polymer coating protects the magazine and prevents deformation even when dropped from a great height. Note: Glock magazines can be very difficult to load when new. Often the last round will not fit until the magazine has undergone a break-in period. It is recommended that the magazine be loaded with all but the last round and left for a few days to compress the spring. Cycling the magazine from full to empty multiple times can assist in the break-in period. Specifications for Glock G17 Gen5 9mm Luger 19 Round Factory Pistol Magazine: Manufacturer: Glock Gun Make: Glock Gun Model: Glock 17L Gen 5, Glock 34 Gen 5, Glock 19 Gen 5, Glock 26 Gen 5, Glock 17 Gen 5, Glock 19X Gen 5 Caliber: 9mm Luger Magazine Capacity: 19 Round Color: Black Fabric/Material: Polymer Package Contents: Glock G17 Gen5 9mm Luger 19 Round Factory Pistol Magazine