This is a Tunze CO2 controller 7074, it's especially great for anyone with a calcium reactor as it allows for precise maintenance of the pH of your tank. It is about 2 years old and is in pretty good condition, it works fine.
I'd like to get $175 for it obo which is considerably less than I bought it for.

http://i111.photobucket.com/albums/n...t/100_1864.jpg
http://i111.photobucket.com/albums/n...t/100_1861.jpg
http://i111.photobucket.com/albums/n...t/100_1871.jpg

Thanks
Aaron