The rubel was the currency of Poland from 1841 until 1917. It consisted of Russian ruble coins and banknotes, together with notes issued by the Bank Polski. The rubel replaced the złoty at a rate of 1 rubel = 6 2⁄3 złotych (1 złoty = 15 kopecks). It was replaced by the marka in 1917.
References
Polish rubel Wikipedia(Text) CC BY-SA