These stickers are similar is style to safety inspection stickers used in the USA, more commonly in the state of Hawaii, and fixed on the back of vehicles. The number indicates the month of expiry and the color makes it easier to recognize from a distance. Use them to track your own registration, or just get your favorite number or color. These do not expire!
The sticker has reflector material
Size: (W) 7.7cm x (H) 5.2cm