This is a pretty awesome deal, I'd buy one of these if I hadn't picked up a logitech 500 a couple of months ago.
These things actually have 5 buttons although it isn't clear on the image.
# 1800dpi Razer Precision 3G Infrared Sensor.
# Five independently programmable Hyperesponse buttons.
# 60-120 inches per second and 15g of acceleration.
# 32KB Razer Synapse onboard memory.
# Zero-acoustic Ultraslick Teflon feet and has a Premium titanium finish.
Review here: http://www.straferight.com/forums/pc-hardware/175054-review-razer-boomslang-ce-2007-a.html