Grade: 25 Material: Chrome Steel (AISI 52100) Diameter: 3/8, 0.375 inches (9.525 millimeter) Weight: 0.12529 ounces (3.5519 grams) PGN’s G25 3/8" Inch Chrome Steel Balls extremely precise and smooth surface guarantees you won't find any defects, such as flats, pits, soft spots, and cuts.