Remanufactured for HP 21 Black MICR Ink Cartridge (C9351AN) – for Check Printing

HP 21 Black MICR (C9351AN) at a glance: a black MICR ink cartridge. Remanufactured: a genuine HP 21 cartridge, cleaned, refilled and print-tested. Fits the HP DeskJet D1311–D2460, F2110–F4180, 3910–3940 and OfficeJet 4315–5610. Backed by a 1-year 100% satisfaction guarantee; orders by 4 PM ET (Mon–Fri) ship the same day from Long Island, NY.

Key Facts

What's in the Box

• 1 × HP 21 Black MICR (C9351AN) remanufactured ink cartridge

Compatible Printers (49 models)

• HP DeskJet D1311 / D1320 / D1330 / D1360 / D1420 / D1430 / D1445 / D1455 / D1460 / D1520 / D1530 / D1560
• HP DeskJet D2330 / D2360 / D2430 / D2460
• HP DeskJet F2110 / F2120 / F2180 / F2185 / F2187 / F2210 / F2235 / F2240 / F2280 / F2290
• HP DeskJet F335 / F370 / F375 / F380 / F4180
• HP DeskJet 3910 / 3915 / 3918 / 3920 / 3930 / 3940
• HP OfficeJet 4315 / 4355 / 5610 / 5615
• HP OfficeJet J3608 / J3640 / J3680
• HP PSC 1401 / 1402 / 1410 / 1415 / 1417

Don't mix these up: This is the MICR (magnetic ink) version of HP 21 black for printing checks. It fits the same slot as the standard 21 black; for everyday documents the standard cartridge costs less.

Not sure? Look up your exact model on our Find Ink by Printer page, or contact us and we'll confirm the right cartridge for you.

Part Numbers & Also Known As

This cartridge replaces or is also searched for as: C9351AN, HP C9351AN, HP 21 black MICR, HP21 black MICR, 21 black MICR ink, HP 21 MICR, 21 MICR, MICR ink, MICR ink cartridge, check printing ink, HP 21 black

Chips, Printer Messages & Installation

Installing: open the cartridge access door and wait for the carriage to move to the center. Press down on the old cartridge to release it and pull it out. Unwrap the new one, pull off the plastic tape by its tab without touching the copper contacts or nozzles, and slide it into its slot at a slight upward angle until it clicks. Close the door and print the alignment page if prompted.

"Cartridge problem" or "incompatible cartridge": remove the cartridge, wipe the copper contacts with a dry lint-free cloth, check that all the tape is off, and reseat it until it clicks.

Streaks or missing colors: run the printhead cleaning from the printer's Tools menu or HP software. The printhead is built into these cartridges, so a cartridge that stays streaky after two cleanings is the likely culprit.

Still stuck? See our guide to fixing a cartridge that isn't recognized or contact us and we'll make it right.

Remanufactured vs. Compatible vs. Original

Original (OEM) cartridges are new from the printer brand and cost the most. Remanufactured cartridges, like this one, start as genuine original shells (including the original chip) that are cleaned, refilled with high-quality ink and print-tested, so they fit and communicate like the original at a fraction of the price. Compatible cartridges are built new by a third party with their own chip. Castle Ink sells remanufactured inkjet cartridges and compatible (newly manufactured) toner.

Other Options for the Same Printers

• HP 21 Black + HP 22 Tri-Color Combo Pack
• HP 21 Black Ink Cartridge (C9351AN)
• HP 22 Tri-Color Ink Cartridge (C9352AN)

Frequently Asked Questions

What is MICR ink?

MICR ink contains magnetic iron oxide, so the routing number, account number and check number printed in the line at the bottom of a check can be read by bank sorting equipment.

What else do I need to print checks?

Check-printing software that uses the E-13B MICR font, and blank check stock. Print the MICR line with this cartridge and everything else as normal.

Will my bank accept checks printed with it?

MICR ink is made for bank readers, but bank requirements vary. Print a test check and have your bank verify it before printing a full batch.

Can I print regular documents with it?

Yes, it prints like normal black ink. It costs more, so most people keep a standard cartridge for everyday printing.

Will this void my printer warranty?

No. Under the U.S. Magnuson-Moss Warranty Act, a manufacturer can't void your printer warranty just because you used a third-party or remanufactured supply. If a non-original supply directly caused damage, that specific repair might not be covered.

How long can I store it?

Store it sealed, at room temperature and out of direct sunlight, and use it within about 24 months for best results. Once opened, install it promptly.

When will my order ship?

Orders placed by 4 PM ET, Monday through Friday, ship the same business day from Long Island, NY, by USPS (2–5 business days). Expedited 1–2 day delivery is available at checkout, and shipping is free on orders over $50.