Buy a combo pack and save! Combo Contents (3) Gen 3 S15 magazines (1) GlockA(R) 43X / 48 steel mag catch black nitride Mag Catch Requirement It is required to swap out your plastic OEM mag catch with either our standard steel mag catch or our premium steel mag catch. Here's why. If you don't swap your mag catch you may have reliability issues. If you use another manufacturer's mag catch you may have reliability issues. S15 magazines were designed to work with Shield Arms steel mag catches. If you have a first generation aluminum mag catch, it is required to upgrade to one of our steel mag catch offerings.