CCT Nozzle Valve Spring constructed with high strength spring steel and hard coating to enhance it durability and stability. 2 different lengths of spring option lets professional user able to equip the proper one to optimise the performance. White Blue Spring is pre-set as balance on Joule power and recoil. Black spring is around 10% increment on Joule power. Highlighted features Made from High Strength Spring Steel Hard Coating Prevents Corrosion 2 different options of spring (White Blue and Black) Effectively balance the Joule power and recoil *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. The actual performance is based on the overall setting on your airsoft gun. Please consult your airsoft gunsmith for advicing.