The SLK974U HSF uses a series of thin bonded copper fins which make up the composition of the unit. The copper fins extend left to right with a set of grooves which allow the positioning of the appropriate sized fan for cooling. The bottom of the SLK974U HSF is machined smooth and has a nice reflective copper surface which should assist with moving heat away from the CPU. Upon closer inspection, I didn't notice any machine or nick marks along the outer edge and center of the copper base.



Link: MTB