Buy the 3 gun spring upgrade its worth it - Fostech Echo AR-II Drop-In Binary AR-15 Trigger

This is truly one of the best triggers and the fact that it is binary was the selling point I will say though if you're going to get this make sure you do the spring upgrade very easy to do all you do is tape up you're trigger so it doesn't fly apart I cannot stress how important that is take the spring out and put the new one in look on YouTube Forest lights instructions