Kannastor aluminum 4 part aluminum grinders. These are available in all aluminum, or solid top and jar body or clear top with clear jar body. Sizes are 2.2" or 56 mm and 2.5" or 63 mm round in diameter.
The Notch Alloy medium size 2.5" 4 part grinder in anodized colors. Each 4 part grinder is made with a non toxic coating. The super hard plating is as hard as tool steel and almost as hard as diamonds. Also these grinders have been anodized to prevent scratching.