These 4-Part Metal Grinders come in 4 different sizes and are all magnetised to reduce content loss. No matter which size you go for, the Basil Bush Aluminium Sifter Grinder is a great piece of kit to own. Each one splits into 4 parts with the top 2 pieces making up your grinder. As you grind, your mixture filters down into the next layer that contains a gauze, which, in turn, filters tiny plant or petal particles through to the catching tray. The residue caught and collected in the catching tray is often the most potent extract of your herbs, spices or petals.