Pulsar Concave Rainbow Anodized Aluminum Grinder | 2.5"The Pulsar Concave Rainbow Anodized Aluminum Grinder has a 2. 5 inch diameter and a concave lid that's perfect for holding herb while you're packing a pipe, joint, or spliff. The grinding chamber features diamond shaped shredding teeth and is specially shaped to funnel herb towards the center for an even and thorough grind. Below the storage compartment is a sifting screen that leads to a pollen chamber which catches precious kief from the ground