The Fan:
It's a small Delta fan and it's very quiet. This 7-bladed fan puts out a very low 9CFM worth of airflow. With a rating like that you begin to realize what class of processor this heatsink should be attach to. The fan rotates at 4500RPM and plugs directly into a motherboard fan header.

Side A:
For all intensive purposes the base is 4mm thick, though it does go up to 6mm at the corners. Two little edges are designed to keep the heatsink from being improperly positioned (a guess?). Each of the nine central fins is 1mm thick, 19mm high, and spaced 2.25mm apart.

Heatsink Base:
The Coolermaster originally came with a green phase change material thermal pad. In all the times we've seen this types of pads previously, the heatsink always operated a degree or so cooler once they were removed and some good thermal goo applied. As with just about every extruded heatsink we look at, the base is domed inward very slightly.