Shield Arms S15 Gen 3 Magazine 9mm Luger Combo for Glock 43X/48 with Mag Release - 15 Rounds - The S15 is a steel magazine, and is the same length as the OEM Glock 15 round magazine, but holds an additional 5 rounds. Features US-based manufacturer. Modular tooling. Raised ribs on the back of the magazine allows these to fully match the OEM magazine position in the mag well, which should eliminate any tolerance stacking that results from Glock frame variations. New steel is slightly thicker, tougher, and now comes with a new standard black nitrocarburized QPQ finish for a high degree of corrosion resistance