M300 (also referred to as 1.2709) is an 18% nickel maraging steel powder producing ultra-high tensile strength and hardness after a simple age hardening treatment, with good toughness and dimensional stability. Its carbon-free martensitic microstructure provides excellent additive manufacturing processability without the cracking susceptibility of high-carbon tool steels, enabling the production of complex tooling inserts, conformal cooling dies, molds, and high-strength structural aerospace components. Qualified to ASTM A646 and AMS 6514, M300 is used across military, aerospace, automotive, and general industrial tooling applications.