It's a spring that causes the trigger to be an 8# trigger. It's actually a joke. I mean it works, but I don't think it will last long. Just glued on. But, that 8# pull feels a lot safer on a SA trigger. MY LCP has a 5# trigger, but the travel distance is pretty long. The LCP II has the same 5# pull, but is a short throw trigger. When I read the the NYC police department used 10# triggers and why, I thought it was a good idea and for me too. Some guys say they have total control in a self defense situation, but I feel I need a little help in making sure I don't pull the trigger too soon. A heavier trigger helps.