Unknown 1969 elevator with rare doors - Quickborn, Germany

The door model of this elevator was quite popular in the Netherlands - allthough there often seen with a round window. It is a rare sight in Germany. In fact, I can't remember seeing any of those outside of NL yet. Interesting. Sadly there is no way to tell who built this one. Maybe even a Dutch company? The serial number 69155 (probably stands for elevator 155 from 1969) doesn't ring a bell. Know anything? Tell me in the comments below...