This is a very good product by BT Design. It is very easy to install. All you have to do is pop the trigger frame then remove the trigger assembly. From here you replace the old trigger. Them you unscrew three screws in the trigger frame. This splits the frame and allows you to remove the old gaurd and add the new one. Put everything back together and you reinstall it into the A5. Its quick and easy.
It works the same as the original trigger. It is good if you like to have two triggers. I have found that it is easier to fire fast with two triggers.
This is a good thing to get if you like the feel of two triggers. It also seems to help you fire faster so i would recommend that you get it because it is only like $20