Have you ever opened your purse in the dark?
In the night, have you ever opened your purse to pay a fee in the taxi?
It is too difficult to recognize paper money which one is 10$ or 5$ in the dark. This is luminous paper money. It emit faint light in the dark although you can not see the light on daytime. It help you recognize to count money in the dark.

                                                                                                                                                It is designed in 2010