The Ghost Inc LoViz MOAB +4 Magazine Extension for Gen 2-5 Glock pistols enhances your magazine capacity while maintaining a sleek, low-profile design for deep concealment. It adds four extra rounds to 9mm Glock magazines and three extra rounds to .40 ACP and .357 Cal Glock magazines. Designed for smooth handling, its ergonomic edges allow for quick and effortless magazine swaps, while the patented perimeter ring ensures a secure fit. This extension also includes an extra power magazine spring for reliable performance. Proudly made in the USA and backed by a lifetime warranty, it's a perfect upgrade for those seeking increased capacity without added bulk. Adds 4-round to 9mm factory Glock magazines and 3-round to .40 ACP and .357 magazines Works with 19X, 17, 17L, 22, 24, 31, 34, 35, 37, 45 and 47 magazines Includes extra power magazine spring for reliable feeding Low-profile design enhances deeper concealment Ensures positive magazine seating for secure and consistent reloads Perimeter ring reinforcement for secure extension retention Tough construction ensures long-lasting performance Smooth ergonomic edges enhance comfort and usability Backed by Ghost's unconditional lifetime warranty for peace of mind