If you are using the Shield Arms S15 magazines in your Glock 43X/48 it is recommended that you upgrade your magazine catch to the Shield Arms Steel Magazine Catch. A plastic magazine catch with a plastic magazine is great. A plastic magazine catch with a steel magazine is less than optimal. They will work but there is also increased wear on the magazine catch. Plastic with plastic, steel with steel is a good guide to follow for magazines and magazine catches. Changing the magazine catch only takes a few minutes and will increase the life of your parts.