55mm Portable Grinder 4 Pieces Metal Zinc Alloy Herb And Spice Grinder. Classic 4-piece, 3-chamber design allows for grinding & storage of pollen. High Quality and Durability: made of strong, high quality zinc alloy for optimal performance and durability. Perfect handheld Size: Small & compact, easy for travel. Magnets to Seal Top along with a Polymer O-Ring.