There are nine magnets in the AirPods Case that can gather a lot of iron/metal dust over time. The guard acts as a buffer between your case and the metallic dust that accumulates over time. The guard can easily be exchanged out if needed. The thickness of the plate is 0.04mm. Experience flawless use of the case with the Dust Guard installed. INSTALLATION 1) Attach the bottom sticker by aligning it with the LED indicator light. 2) Place the top sticker upside down on the bottom sticker so that the adhesive side faces upwards on the body portion. 3) Close lid over the upward facing dust guard so that it sticks perfectly to cap once shut.