FrostyTech posted a review on the Apack ZeroTherm BTF90 Copper Heatsink

The Apack Zerotherm BTF90 and BTF80 heatsinks are the companies' first consumer class heatsinks for the AM2 platform, and in spite of the kitschy 'butterfly' shaped cooling fins the BTF90 is surprisingly effective. The fan spins at 2500RPM and includes Pulse Width Modulation (4-pin PWM) speed control, a feature that is being adopted by motherboard manufacturers for both Intel and AMD platforms.

Apack ZeroTherm BTF90 Copper Heatsink Review