Numbers that are visible on both sides of the paper create an extra challenge for criminals attempting to reproduce the document. Laser printers and photocopiers can't achieve this effect. Security Thread Paper - Distinct vertical threads are actually woven into the fibers of the paper. This is the same type of thread used in most U.S. currency. This technologically advanced paper is virtually impossible to reproduce with convincing accuracy.
Illegal copies are obvious.
Laid Lines - Irregular lines in the paper that make duplication easy to detect. Laser Treatment - A treatment to paper that makes it difficult to remove toner from laser printed documents.