Hepco made two different models for w113. For the 230SL model, the case was similar in design to yours but with a lock that had a rounded end. The hardware was brass and the vinyl covering was brown. For latter models, the locks became somewhat rectangular in shape (chrome plated) and and the vinyl was black. Both interior were lined with a nylon moire fabric in either cream (with the brown vinyl) or grey (with black). The set came with four pieces. A large rectangular case, two matching smaller cases and a hard sided make up case. The photo attached does not show the make up case. You can also find a photo of the 230 set in the technical manual on this site.
I believe your luggage was made much later when luggage was no longer offered by MB.
