I also have quality and fitment issues with the ECS smoked side markers. And have actually had issues on both my first and second shipment. In all fairness, ECS has worked with me up to this point, but I did want to make people aware of the issues I have.
In the first set, the right (passenger) lens was scratched:
ECS immediately sent a replacement set, but the second left (driver) lens had foreign material embedded in it:
So between the two sets, I ended up with one left and one right sidemarker that are cosmetically good. However, neither has very good fitment in comparison to the OEM parts.
The left one sits pronounced and only loosely snaps in place:
The right one is pronounced on the front lower corner but does snap more securely in place:
And I also wanted to point out that the statement on ECS' webpage, "ECS light housings are ultrasonically welded to seal them tight", is misleading and/or inaccurate. Of the 4 pieces I received, none of them were air tight (simply blowing into the light bulb opening to test).
At this point I am leery to try a third set from ECS. APTuning is working on fitment issues with theirs. So far I have only seen positive comments about the ones from OEMPlus (johannes post #25):