Lundahl silver moving coil step up transformer. Model 1931AG. This unit has switchable gain from 18 to 26 db. I have only ever used the 18db. setting as that setting worked best on my .5 mv Grado Statement cartridge. Moving coil step up transformers use many turns of wire to increase the voltage as needed. This is where silver wire provides a benefit over copper wire that goes from good to great or amazing sounding. I have used or heard many step up devices for this application this transformer is the best sounding device of its type that I have ever come in contact with and my friends agree. I also consider this to be an absolute bargain for the price.