The inlet and outlet direction, and it's size. The GE ones are roughly 6cm x 6 cm. These murata ones are 2cm by 2cm.

http://www.digikey.ca/product-search/en?FV=fff40012,fff80051...

Damn, I think I found myself a christmas present. Pity it's so small though. I'll have to look at some numbers and see if it's good enough to cool a desktop's cpu heat sink.