Yoshihiro Mizu Yaki Aogami Super Blue High Carbon Steel Kurouchi Petty D-Shaped Shitan Handle (6'' (150mm) & No Saya) Recommended to purchase Custom-Fit Saya Knife Cover and Knife together Blade Material: Aogami Super Blue High Carbon Steel / Knife Type: Petty ( Utility knife) Super Blue High Carbon Steel core (HRC 64-65) is known for its exceptional sharpness, high edge retention, and ease of sharpening. Blade: Double-Edged / Blade Length: 6 Inch (150mm) High Carbon Steel Knives require maintenance in order to prevent oxidizing.