Hello

I have a double strop, but I expirience difficulty with idenifiying which side is what. Could you please help me?

The black side which is above all others is black hard skin. Is it this side I suppose to strop on before shaving?

What about the second strop below, the white one? It has two sides: one side is like hard paper and the other side is a skin like the black one, but softer.

I am pretty confused about all these sides.

Here is some photos of my strop: