I have the YHM Spectre kit on my 16" upper. Quality and value for what you get is great. Their customer service was great, the gentleman I talked to measured parts for me over the phone. If I had one suggestion, it would be to get the lightweight version of their handgaurd. Not that I don't like being able to beat a bear with my AR, but we don't have many bears here in Arizona, at least not big ones.