Styli, or singular ‘stylus’, replacements are designed to replace the removable stylus on the end of a moving magnet (MM) cartridge so that you only need to replace the stylus when the needle wears out rather than having to replace the whole phono cartridge. Over time, sound quality will be affected as your needle wears, and it could even cause damage to your vinyl records. Each stylus fits a specific model cartridge, so it’s essential to select the correct one.