SharpStone Brand absolutely stands up to the $100+ grinders on the market with its razor sharp diamond cutting blades that provide extreme efficiency. These 4 piece hard top grinders are made of aircraft grade aluminum rod using the newest in CNC machine technology with a thin poly ring for a smooth grinding without friction. SharpStone grinders are anodized for a smooth finish, meaning there's no wear or smudge marks. SharpStone grinders are also equipped with powerful neodymium magnets to help keep them closed. All 4 piece SharpStone grinders come with a protective carrying pouch and a pollen scraper.