Thank you for your interest, the CO2 cartridge is inside the the top of the keg. Because of its location I cant take a picture of the cartridge itself. The replacement CO2 unit which includes the cartridge, regulator, and actuator are $5.50 plus shipping. Huber is a German company and the shipping can be as low as $7 and as high as $15 depending on your location. Because of the high shipping cost I am selling lots of 4 for $30. I have a large inventory of these and this deal will stay up till their all gone. If you have anymore questions let me know.
I brew like I cook....prolly won't be able to recreat anything I make but i'll try to improve on it