I exchanged some emails with RK Photographic and it looks the Condenser nš1 i have is for medium format. They say that existed a Condenser nš2 but the former (nš1) is so good to print 35mm that there is no need to buy it. The only difference could be a longer time (maybe seconds) to print 35mm.
The prints looks so good and with this confirmation I won't do anything and keep printing :-)
Thanks again for the help.