Like I said, I have three of them. One is used for a 9mm AR. I've tried various top ends on them and they all fit like a glove.
My 9mm carries a Rock River upper, the other two have a newer Colt upper and an Armalite upper. Out of the three, the RRA fits the best to my taste being a snug fit. Not tight, but snug enough to allow the the pins to be removed with the push of my thumb. Wasn't that way at first, but after shooting a few hundred rounds, it loosened up just right. The RRA fit so well, I could swear that the RRA upper and Dlask lower were made by the same machine. However, I always wondered if in their beginning, Dlask didn't have RRA make their lowers and Dlask just roll marked and anodized them. They are also very, very close in color.
The three Dlask lowers I have are one of each of the different style they've produced so far. The first one has the white markings, one has the blind recessed markings with the small maple leaf and the third is their most recent with the larger maple leaf like M_A_T_T shows in his avatar a few posts above.
The first lower Dlask produced was one that would not seat the thermold mags because of their magwell diamention and the thermold mag trim around it not being able to clear that bottom of the magwell and that particular lower. The anodizing was done a bit thick, so some non-milspec mags would not drop free.
The buffer retainer pin hole also needed some cleaning up as the it contained some excess crap from machining and got solidified in that hole with anodizing. All else was a charm. The next two I bought fit perfect with the Armalite parts kit I installed. I've installed other parts kits on Dlask lowers too and found they work as well, 'cept I'd suggest you stay away from DPMS parts.
Oh, another issue I remember was the bolt catch pin was hard to fit, but did with some persuasion. Now I use spring pins to assemble lowers, so I don't know if this is still a difficult task.