Mechanically locked piston driver interface. This professional piston drive is for MAX CN70 coil nailer. Heat treated S7 steel at the tip of the piston to Rockwell hardness of 55~56. The cap end is at about 52. The piston driver cap is made of Aerospace Aluminum grade 7075. A brand-new, unused, unopened, undamaged item in its original packaging. Return refund: If you have any questions, you can refund in full without any problems