379 is medium grit diamond, football/egg shaped diamond bur used for occlusal adjustments on fillings. FG 314 shank. Head Diameter size = 023 (2.3mm). For Occlusal/Lingual reduction. Working Length of Diamond Grit Part = 4.2mm. USA Reference number = OSD1 or DOS1Recommended Max. Speed = 300,000rpm. Matches H379 Carbide finisher series.