Got a new batch of coils to evaluate (D585) and they use the same connectors as the D581s I'm using now (wired direct without connectors).  The D585s have the external heatsink that Bob White mentioned earlier.  It is interesting that these coils are listed as the 2nd version of the D581.  Not that I would expect it, but there is no reason given for the redesign. In view of my experience with the D581s I can't help but wonder if the external heat sink was added as a fix for heat related problems. 

 

I'll find out soon since I'm still running 3 of the D581s. 

 

Tracy