150% hammer spring was made by high strength spring steel which is able to increase the power for each valve punch. It is suitable and more reliable in hot weather environment or high-pressure condition to ensure a consistent valve movement in every shot. Compatible to TM M&P9, M&P9 V Custom and M&P9L. Highlighted features Made from High Strength Spring Steel Hard Coating Prevents Corrosion Provide extra hammer power Workable even in extreme weather or high-pressure environment *PS: Please note: installing parts / assemble /fitting airsoft gun will need intermediate knowledge; for expert or airsoft gunsmith. Please refer to your airsoft gunsmith for proper installation/fitting. Fitting may be needed as the condition of each airsoft gun might be different. Regular maintenance is needed for all airsoft guns in order to keep it in good working condition and reduce wear out issue on parts.