Classic edition 4 piece alloy herb grinder. Magnetic Lid, Grinding Compartment, Pollen Screen & Storage, Cleaning Tool. HMP Large Grinder comes with a magnetic cap, holding chamber, and kief catch. The 63mm circumference and zinc alloy ensure a smooth grind every time. Classic edition 4 piece alloy herb grinder. Magnetic Lid, Grinding Compartment, Pollen Screen & Storage, Cleaning Tool.