I have an S.I. Defense Lower married to my BCM Middy. I like it.

They are not top of the line, I actually had to send mine back...mag well was tight and mags were not dropping freely.

SI paid for the return shipping and all told I had the lower back 1 week after I sent it to them. A couple other people from CalGuns also bought lowers from them at the same time and had the exact same issue. Seems like it was a batch issue. Sonju took care of everyone who had an issue.

FYI, I paid $125 for my lower from them.