Counterfeit camera gear is a growing problem. While fake cameras are rare, fake accessories (batteries, chargers) and even tampered lenses do circulate. A serial number check ensures that the item you hold matches the manufacturing records of Canon USA.
The serial number's location varies depending on the type of device you own: Canon Serial Number Check Usa
Look at the rear of the lens. There is usually a 10-digit serial number (e.g., UU0402C 1234A ). The second character indicates the year, and the next two indicate the month. Counterfeit camera gear is a growing problem