letters are random, not fixed. The anti-counterfeiting number is a group of four digits * * * and consists of four groups of sixteen digits:

1. Color-changing ink. The words Shell Lubricating Oil on the first label are printed with color-changing ink, and the color will change when viewed from the angle of light transformation. See the figure, which is genuine.

2. The drop of water disappears. Drop a drop of water on the word genuine on the first label, and the word genuine will disappear. After wiping off the water, it will reappear after a while. This is genuine.

3. laser holographic film, uncover the first layer of label, and look at the reverse side of the label from different angles, which will show the trademark of Shell, which is genuine.

4. Barcode, the barcode on the label of each barrel cover of Shell lubricating oil is unique. This is authentic

5. Micrographics are linear to the naked eye, and the lines are composed of the words SHELL under the magnifying glass, which is authentic.