This label is used on multiple BMW models to note that the power steering system uses CHF 11.S hydraulic fluid instead of traditional ATF. This is a stick-on label that is sized to fit on the existing cap. It will even cover the existing "ATF Only" text on the cap.
The correct label on the reservoir can prevent catastrophic failure in your steering rack so it's important to have a clear label on the power steering reservoir cap.
OEM fluid supplier Pentosin offers synthetic CHF or petroleum-based EHF. Both are compatible with your car's steering and hydraulic system. The green CHF label applies to EHF as well.