CMC Products RPM or Railed Power Mags are some of the STRONGEST 1911 MAGAZINES 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. .45 ACP Caliber Fits All Full-Size (Government Model) 1911 Handguns 8 Round Capacity At Least 2X the Service Life over other 1911 Mags Feed Rails Provide Smoothest Feeding Surface Heavy-Duty Corrosion Resistant Stainless Steel Body Laser Welded Tube Numbered Witness Holes for Visual Round Count Patented RPM Follower is Alloy Frame Safe 18 Coils of High Tensile Rocket Wire Spring Removable Base Pad for Easy Cleaning Smooth Finish for Easy Insertion / Removal Long-Lasting Function in Dirty Environments CMC's 100 percent Satisfaction Guarantee