I have been using 4 Koolance VL4N QDCs on my current build. I am more than satisfied with their performance, plus they greatly help with all the loop maintenance. However, i'd like to get more compact QDC's without sacrificing the excellent flow these give my loop, as they were quite of a hassle to get into my case. I have been looking at Koolance's QD4 series, but i was wondering if there were any other compact, high flow QDC's.