Aerospaced grinders come with 4 and 2 Pieces. Sifters are made from one solid block of aluminum. Alumium that is used for Aerospaced grinders is used in Aerospace technology. It's very solid and will last for a life time.
These grinders are great for any dry herb mix that need to be ground.
Aerospaced grinders have an anodized metal that ensures that the coating will not end up flaking in your grinds and will not scratch away.