SANDVIK R390-17 04 50E-PM 4240 milling inserts The listing is for 2 packs = 20 pcs.: 'FACTORY SEALED' grade 4240 (HC) – P40 (P35 – P50) - Tough coated carbide grade for demanding operations in steel milling. For end mill and square shoulder concepts, grade GC4240 should be used in more stable conditions, such as short overhangs, face milling, shallow shoulder milling, etc. For other concepts, grade GC4240 is the first or backup choice in toug