HP LaserJet 4000, 4050 series laser printers - MICR SECURITY Toner for printing CHECKS (approx. 10,000 Yield). This toner creates a red stain if text alteration is attempted.
The "security" brand Troy MICR cartridges have a specially blended MICR toner which turns RED if someone attempts to alter or change your check with any type of solvent.