One is a reach reduction kit that has the old style less curved trigger and a new disconnecter that locates the trigger a bit further back when the hammer is a rest. A lighter spring steel trigger return spring and a new extended firing pin, and a slightly lighter hammer mainspring that they gaurantee will reliably ignite all primers whether in SA or DA mode. Blake is in town until Saturday when he's being shipped off to South Korea so I'll probably wait till then to start a gun smithing project but I'm looking forward to seeing how it all works together. The trigger being set back should solve one of the two problems I have with this gun and that's my fat trigger finger getting pinched between the frame and the trigger in the trigger opening...that edge is sharp! The other problem is a very sharply curved trigger hurts the tip of my finger and this new trigger has a much more natural curve that feels immensely better. Also, I think it won't crowd my finger up at the top of the trigger guard where it can get pinched.