M.I.C.R. Toner cartridges
M.I.C.R. stands for "Magnetic Ink Character Recognition". It is a special toner formulation which contains micro-fine sized magnetic particles, which when used in a laser printer, produce text upon paper which can then be electromagnetically read by special readers.
These readers are like scanners, but they operate very quickly and can accurately detect the encoded symbols that you would see on the bottom of checks.
It is true, that M.I.C.R. imprinted documents are more secure and are actually processed by M.I.C.R. readers must faster and more accurately than Optical readers.
Many people have the option to print their own checks from blank check stock. There are many uses for printing one's own checks and other security instruments. For example, if you manage multiple properties, or are a financial advisor in charge of managing disbursements of checks, etc., then with proper software, you can run checks for many clients using the same check stock and same software package. There is money to be made, by printing checks for clients in this fashion.