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121st cartridges have the usual and there with extended ink. Externally they are the same-differences inside.
Open usual 121st cartridge (black). Top cover to the housing consists of a single piece of plastic, it should be split off. Will make a tidy-excellent. Will not work accurately-do not worry, just be harder to attach in place. Helped me chisel with a hammer, a knife just could not otkovyryat.
Inside, in the center of the ink tank with a sponge, and around the air (in the ink tank as previously poured them there, thinking capacity reported).
Pull out the ink sponge.
At the bottom of the ink tank is visible filter. In this case, he stabbed as he had once pierced, but that did not make the print cartridge was. Pierce the filter should not be unnecessarily, although this does not prevent opening the cartridge to continue printing.
increase capacity cartridge
You can break all the barriers, one can break, but you can make a small hole at the bottom of the container to combine the two chambers.