This is the ProMag FN 509C 9mm 15-round magazine.

Save some of your hard-earned money without sacrificing reliability with this 15-round FN 509C magazine from ProMag!

Everything about this magazine exudes durability, from its heat-treated steel body to the impact-resistant polymer floorplate. Internally, an injection-molded polymer follower and chrome silicon wire spring provide the reliability to match. 

Your FN 509C is versatile enough to handle almost any task, so you can never have too many magazines ready to go! Plus, ProMag backs its magazines with a lifetime warranty, so you can rest easy for many rounds to come.  

At this price, you might as well order a few!