Kydex Customs FNX .45 Magazine CarrierOur FNX . 45 Magazine Carriers are designed to work with VFC Cybergun FNX . 45 Magazines as well as Tokyo Marui FNX . 45 Magazines. All of our Pistol Magazine Carriers use an MRD (Magazine Retention Device) which provides adjustable retention to the front of the magazine, allowing the carrier to hold on to the magazine with the perfect amount of resistance. To adjust the retention on the Magazine Carriers you need to screw or unscrew the silver grub