(1) Gen 3 S15 magazine black nitride (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 the Shield Arms standard steel mag catch or their 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. Gen 2 and 3 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.