the F5 MPX 50 round drum magazine has been re-designed again ? Based on the Second Generation Sig MPX, it?s machined from 6061 solid billet aluminum, and painted with ceramic-based Cerakote, it is built with extraordinary quality & performance in mind. Our most recent review of the Sig MPX revealed that the feeding system is not symmetrical. The larger of the two feed ramps favor the left side, as a single feed magazine design, we want to do the same, so we ?mirror-imaged? our original design and found that this is much more reliable. We also wanted to make it more compact and low profile than it already is, so we shortened the body by 9mm, this allows it to lock in as close to the magwell as possible. Best for Sub Gun competitions, home defense, target practice, and just overall looks.