THE COPPER STRIP ALLOWS STATIC ELECTRICITY TO DISCHARGE FROM THE DRUM TO EARTH. SQUEEKS ARE NORMALLY CAUSED BY WORN OR DRY BEARINGS,DEPENDING ON THE MAKE AND MODEL,IT COULD BE FELT,NYLON OR A PHOSPHUR BRONZE BUSH BEARING. IF THEY BECOME WORN YOU HAVE METAL TO METAL CONTACT.
THE SPIN DOCTOR(KEITH), January 2005