The High quality blue cermaic disc is one of the best abrasive discs available on the market! its less expensive to use than most other discs, and it will give great and lasting results. Ceramic (blue) grinding disc, premium: 150 x 3.2 x 16mm, for sharpening 1/4, .325, and 3/8 low profile chains with Triplematic and Sensomatic.