Produced in 1962 by Fablok factory in Chrzanow/Poland. Now in the Railway Museum in Warsaw.
SM25 is a C locomotive, what means there are three powered axles under the unit.
It is run by a four-stroke diesel engine and the power is supplied to axles through hydraulic transmission.
Only three units were produced in Fablok factory in the period of 1961 - 1963 due to severe problems with importing hydraulic transmission devices "Voight" from Germany.