(28ml) 28ml Magenta Code C4837AE. HP No. 11 ink cartridges are separate single colour cartridges with built-in smart chips. They are a key component of the HP Modular Ink Delivery System delivering ultra-small ink drops for exceptionally refined print quality at superfast speeds. Each No. 11 colour ink cartridge remains static in the printer and is connected by a pressurised tube to an individual replaceable printhead designed for long service and lower printing costs.