Precision CNC machined carbon steel construction Reduce the friction and abrasion with contacted parts Durable construction prevents flexing and warping under hard use Drop-in upgrade part Silver Zinc Coating For TM G19 G19 Steel Trigger Lever was specially designed for heavy use and capable for high tense competition needs. It constructed by a single piece of steel with CNC machined. Its strength hardening structure ensures the lever was in perfect shape and consistently transfer the force directly to the sear, gives the user a solid and smooth trigger pull feeling. Also, zinc coating is used for reducing the friction to every contact point, keep it run smoothly and minimize abrasion. *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. The 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 the issue on parts. The actual performance is based on the overall setting on your airsoft gun. Please consult your airsoft gunsmith for advising. Strong Screw glue is needed for installation. Use a drop of screw glue when installing the screw and wait for it to dry out overnight. Damage could be caused to the screw thread if screw glue was not used.