CMC Products' RPM or Railed Power Mags are the STRONGEST 1911 MAGAZINES EVER MADE! The RPM design is the result of a relentless pursuit of excellence"" maximizing reliability and durability under all conditions. The dual wall feed rails have revolutionized 1911 magazines. No more jams due to thin"" warped and bent feed lips! The feed rails built into the RPM are AT LEAST TWICE AS STRONG as any traditional 1911 magazine feed lips and provide the SMOOTHEST FEEDING SURFACE.