This kit replaces parts #29, #30 and #31 in your KJW KC-02. The bolt stop, the bolt stop spring and the small pivot pin.
The new bolt stop is custom-designed by RogueWorx and made from a hardened tool steel, similar to that used for lathe cutting and machining tools! This makes it virtually indestructible unlike the standard bolt stop which is made of weak pot metal which is prone to bending and snapping.
Installation video here: https://youtu.be/evz-h8Lu9Ls