We were so excited to use these lockers, which we didn't see anywhere else during our tour of…read morenorthwestern Germany. These lockers are operated by a key card issued to you after payment. It accepts both cash and credit card. Upon payment the roller shutter opens, and we were able to fit all three pieces of our carry-on luggage inside. Once the shutters close, the only way you can retrieve them is with the key card it had issued to you. When you present the key card, the compartments inside shuffle around until the compartment with your bags appear. It must be like those puzzles when there is probably only one empty block of space inside and an algorithem has to move the other blocks which are occupied with other luggage around until yours are ready to exit through roller shutter. EUR6 for up to 24 hours' storage