I have this fan controller and these fans on my highboy. I don't see any reason this controller needs a set of additional relays for the fans but when I was just testing them fan 1 turned on at 182 degrees and then shut off at 180... According to the directions the fan 1 should shut off 10 degrees below turn on temp... it then turned back on when it got to 182... I adjusted the temp screw so am thinking maybe it acted as though it turns on at 190 and shuts off at 180. Ill have to find out tomorrow but wanted to make sure I don't need a relay or something between this controller and fan set.

http://www.summitracing.com/parts/der-16789/overview/
Adjustable : High Amperage Adjustable Dual Electric Fan Controller, 3/8" NPT Thread In Probe

http://www.summitracing.com/parts/der-16927/overview/
High Output Shrouded : High Output Dual 13" Electric RAD Fan/Powdercoated Steel Shroud Kit