GLOCK magazines are 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. Features: Constructed of hardened metal encased in durable polymer Viewing windows for visual confirmation Double-stack design Metal magazine spring Enlarged front of the black polymer base plate Orange follower Specifications: Manufacturer: Glock OEM Model: 17 Caliber: 9mm Capacity: 17-Rounds Standard Magazine for: 17/34/47 Also fits: All Glock 9mm double stack guns