Axle Pivot Pin for Ejector on the trigger pack used bu the HeckFire, as well as all HK and clone trigger packs. This is the style that does not use the axle clip, which is what I recommend for the HeckFire triggers. It will work in all OEM trigger packs, it just will not ‘snap’ in place. The clip is not strictly necessary, as the lower retains the pin in place.
If you are installing the HeckFire as a replacement for your trigger pack, you would move this part (along with the ejector and the ejector spring) from your old pack to your new pack. However if you are building from scratch, you will need to source this part.