I'm venturing into the AR-15 game! I don't know too much about them but here's what I ordered.... A2 config, iron sights, 20" HBAR barrel (5.56), and the rest is standard military spec (trigger, grips, etc.). It's a kit (I have the stripped receiver). My S-I-L is going to help me put it together. This is going to be a good learning experience for me about the platform. Then I had to order 1K rounds too!! I look forward to checkin gin with you guys on this project.