- Czechoslovakia - Maker: Progress of Žilina - Good, Original Condition - Labeled Jr. This piece is attributed to the mentioned designer/maker. It has no attribution mark and no official proof of authenticity, however it is well documented in design history. I take full responsibility for any authenticity issues arising from misattribution, Up to 250V (Europe/UK Standard).The wiring of this item may be original and might need replacement, if not specified otherwise.