Rancilio's espresso grinders are reliable little workhorses. As much at home on your kitchen counter as in a small business or cafe, they can serve a proud owner for many years with proper care and maintenance. While burrs shouldn't need to be frequently replaced, they will dull after a certain amount of throughput, especially in high volume environments. When that happens, you can purchase these Rancilio-made burrs to replace your existing ones, rendering your trusty Rancilio espresso grinder almost as good as new! Rancilio replacement grinder burr specifications Top & bottom burrs included Fits Rancilio Rocky, MD40, Kryo ST & Kryo OD grinders (please pick the correct size from the drop down for your grinder) 50/64 mm outside diameter Made of stainless steel