151a / 152b - 1940 set

This is a very special set owned by a dutch collector. This set dated 1940 is unhreard of so far, it has not been published in any document. The label has no model name or reference number so that it can be used for any model.Any comments ?

Remarkable, Jacques, this 'Economy Label'. Is there a cardboard base insert, with recesses exclusively suitable to accommodate these very models? May be you can let me know privately who this Dutch collector is? Kind regards, Jan