Featuring durable polymer construction, the FN® Five-seveN® 5.7x28mm 20-Round Factory Magazine is built for lasting strength and durability. This factory magazine boasts numbered witness holes for quick, reliable round counts on the fly and removable, impact-resistant polymer baseplates for easy cleaning and maintenance. The durable polymer follower and high tensile steel spring ensure smooth, reliable feeding every time in high-stress target and tactical environments. The FN Five-SeveN redefines futuristic. Constructed primarily from their high-strength polymer and chambered in a proprietary, purpose-built round, the Five-SeveN set a new standard for lightweight firepower. This FN Factory Five-SeveN magazine plays a large part in that innovation; packing a massive 20-round capacity without having to deal with finicky extensions or baseplates, these Five-SeveN mags offer incredible capacity without giving up any reliability.