The Shield Arms S20 is a patented 20-round steel magazine for the Glock 43X and Glock 48. Built on the same staggered-geometry platform as the S15, the S20 pushes capacity even further, giving you 20 rounds with no extension and no baseplate swap. The added capacity extends slightly below the grip frame, making the S20 the ideal high-round-count backup magazine rather than a flush-fit carry mag. Integrated over-insertion tabs stamped into the steel body prevent the magazine from being seated too far into the magwell, protecting feed lip alignment and reliability Requires a Shield Arms steel mag catch-not compatible with the OEM polymer mag catch. Features: 20-Round Capacity: Patented staggered-geometry steel body delivers 20 rounds of 9mm in a single-piece magazine-no extension required Built for Backup: The highest-capacity spare magazine available for the 43X/48 platform, sized for a pocket, mag pouch, or bag Over-Insertion Tabs: Integrated tabs stamped into the steel body stop the magazine from over-seating in the magwell, protecting feed lip alignment and preventing over-insertion malfunctions Steel Construction: Formed steel body built to the same manufacturing standard as the S15 for long-term durability under high-volume use QPQ Nitrocarburizing Finish: Black nitride surface treatment increases hardness and delivers superior wear and corrosion resistance Purpose-Built Geometry: Engineered for reliable, drop-free operation with the Shield Arms steel mag catch Spring for Life Guarantee: Wear out your spring, get a replacement free, for life Made in USA: Precision-manufactured in the United States to Shield Arms' standard tolerances