Is this water pump or water filter?

Hi, I was thinking of buying this pump, but is it a water pump or a water filter,

http://cgi.ebay.co.uk/Atman-Water-Pump-%2f-Hydroponics-%2f-Sump-Filter-AT104_W0QQitemZ120391173018QQcmdZViewItem?rvr_id=&query={query}&fitem=120391173018&linkin_id=3055020&mt_id=635&kw={query}

p u m p

p u m p
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It got me confused with all the bits that come with it, it looks more like a air pump, thanks for your help.