The HP 991AC Magenta (X4D13AC) is an original HP PageWide pigment‑based ink cartridge designed for high-volume professional printing. It delivers a page yield of up to 16,000 pages (at 5% coverage), making it ideal for businesses and offices that run many color pages. The cartridge holds 187 ml of ink.  It produces vivid, stable magenta tones that resist fading and ensure consistent color across large print jobs. Compatible with a range of HP PageWide Pro/Managed printers, such as the P77740dn, P77940dn, and E77660z+ models.  The cartridge dimensions are approximately 215 × 35 × 48 mm and its weight is about 0.23 kg.