These 4 piece hard top grinders are made of zinc alloy and feature razor sharp diamond cutting blades that provide extreme efficiency. These 4 piece hard top grinders are made of zinc alloy and feature razor sharp diamond cutting blades that provide extreme efficiency. Infyniti grinders are anodized for a smooth finish and are also equipped with powerful neodymium magnets to help keep them closed. All 4 piece grinders come with a pollen scraper.