Our grinding burrs suits different kinds of high end coffee grinders. Both for espresso and filter. Our most popular burrs are the coated ones. The coating is to protect the the burrs and make them produce excellent tasing coffee for a longer period of time. Our hardest coated is the Silver Knight which is a semi-DLC coating. DLC stands for "Diamond Like Carbon". As the name suggest, it´s atomic structure reminds of a diamond, but is not as hard of course. We recommend this type of coating for filter coffee. Our Red Speed coating is recommended for espresso after numerous blind tests. The Red Speed is not as hard as the Silver knight but still 30% harder than Titanium Nitrade coatings.