Ed Brown performance magazines for Glock 9mm pistols combine traditional craftsmanship with modern materials, featuring a steel liner encased in a durable polymer shell. Built to Ed Brown's exacting standards, these magazines come in 15, 17 and 31-round capacities. They fit pre-Gen5 model 17 and 19 pistols, with the 31-round version also compatible with any 9mm Glock and AR 9mm platforms accepting Glock-style mags. Designed to outperform factory magazines, each is backed by Ed Brown's lifetime warranty for peace of mind. Polymer outer body performance journal - a comprehensive guide to advanced materials and innovations in high-performance engineering and design Ultimate guide to maximizing efficiency and durability in industrial applications A comprehensive guide to enhancing durability and efficiency in modern flooring solutions Premium spring performance journal - elevate your understanding with in-depth insights and expert analysis on spring dynamics and performance optimization Round count witness holes are strategically placed openings on a firearm magazine, allowing users to visually verify the number of remaining rounds