This “New For 2007” replacement firing pin is designed after the original Russian design. And, it will fit all SKS’s. Even pre-51 versions. But, with pre-51 versions you’ll need a different spring. This is due to the hole in the bolt being drilled deeper in “later” versions. This new firing pin will eliminate slam-fire and uncontrollable full-auto incidents! And, it will allow the use of “soft primered “American” ammo, or reloads. "Kit" includes firing pin, spring, extra spring, written instructions and a pic to aid in installation. Shown above (without spring) , middle (pre '51 Russian SKS) and lower, (all other SKS). Made in USA.