Duty Free on board
Duty-free items purchased on board an aircraft may be carried through the security check if they are enclosed in a transparent special bag (known as an STEB) that has been sealed by the sales clerk. This bag must contain a receipt indicating the date and place of purchase which can be read from the outside. This ensures that you can change planes at other EU airports without any hassle when carrying duty-free merchandise. The bag must remain closed and sealed until you reach your final destination. This applies to the security checks at Frankfurt Airport and all other airports in the EU, Norway, Iceland, and Switzerland.
There is no limit on the number of duty free bags that you may carry on board. Please observe the applicable customs and import regulations.