It is a WKM that I got when they first came out. WAY before Naza. I was flying Mikrokopter on my large machines then but wanted to test the WKM. Henece the 450. Its stayed on there to this day and was always used as a test machine for FW. All my commercial machines fly with WKM.
Yeah My first wkm was installed on a f550. This is how the packaged it. You could get a free 550 frame with your order of a wkm. I think this was 2011?