Pay the extra and get the fostech gen ii echo trigger - Fostech Echo Sport AR-15 Binary Trigger

The good is, it is not a bad install and once installed it does work. What I do not like about it IMHO is the deal killer as far as buying another or recommending. The selector to go from semi to echo is inside the trigger well up against the frame and I subscribe to, "you do not put your finger inside the trigger well unless you are ready to fire!" Another problem with this selector is it is attached to the trigger group in such a way that when you pull the trigger back to fire, the selector itself moves downward a little. Only a little but this does cause a gap between the selector and the frame. Unlikely but any debris that may be flying in the air could get caught between the two and then you would have a failure until found and cleared. Again, while I think that would be rare, it could happen and "Murphy's Law" would have this happen at the worst possible time. You standard safety is still part of the equation. If you have the weapon on safe, it will not fire. Move it to fire and you have semi if the other selector is in the semi mode. Moving that second selector to echo gives you the echo firing mode. The Gen II has all the controls in the standard safety position where you select, safe, semi, or echo. Cost about $100 more but well worth that as it is reliable, easy to use, and no pear of debris locking the thing up. Add the extra $$, skip on this and get the Gen II instead!