Kydex Customs MK23 Magazine CarrierOur MK23 Magazine Carriers are designed to work with All brands of Airsoft MK23 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 screw found on the side of the carrier