The inside part of the shield is coated anti-fog coating. The anti-fog coating can come off easily if you get to touch frequently.
In case of cleaning the shield Using petrochemicals or solvents. RTS (Mirror) of the surface coated can be easily taken off. When cleaning, Please using water and mild detergent or wipe with a soft cloth.
The best way is to confirm its model name on the helmet shield you have. If you see the left or right top side of shield, there would be MODEL : HJ-XX. After you confirm it, you can purchase the same model's shield.