SLX version 2.0 four piece grinder are coated inside and out with a Non-Stick Ceramic Coating that was developed from materials that reduce friction on industrial blades and cutting tools. Every lip, every tooth - even the pollen chamber. While your SLX wont generally need cleaning, if your herbs have an exceptionally high moisture content (greater than 12%) or you use it an extraordinary amount, you may see some light buildup. To remove material that does accumulate you can 1. Tap the grinder lightly on a solid surface (we recommend doing this over a piece of paper so you can collect everything that comes out) or 2. Brush out anything that remains with a toothbrush or other soft brush. Everything will slip right out. The coating is bonded at the molecular level with the aluminum, its 100%non-toxic, FDA approved, and doesnt burn. The 2.4" model is the standard 62mm size. The unique screen design eliminates threads. The screen easily drops into place in the bottom section and screws securely to the 2nd stage. With out the screen the bottom stage stores 3 grams. The coating is extremely durable and any part that ever fails will be replaced at no charge to you. SLX puts their URL on the bottom of every grinder for a reason.