Zwiebelmuster Dudelsackpfeifer 18 cm original tschechisches Porzellan Dubí 2. Wahl

The product is very safe to use - more at http://www.zwiebelmuster.eu/zertifikat-zwiebelmuster/
In Czech Republic, There are many producers of Blue Onion Pattern, but only Bohemia Blue Pattern from Dubi using this trademark:

 
 
The trademark has been modified over the years. More you can find here: http://www.zwiebelmuster.eu/geschichte/