Upon receiving my tax refund this past week, a surge of RAD hit me and I bought a 1963 I2 Gillette Slim Adjustable off of Etsy in very good condition for about $32, which appears to be a steal or at least a slightly better price than the same model sold from different vendors.. It is not only my first adjustable razor, but also my first "butterfly open" model as well. Could someone coach me on the basics of using this thing? Of what metal is it made? What exactly does "adjusting" it do? What do the numbers around it measure? Do I adjust it with the doors open or closed? How do I know if I am twisting the knob too many times? Thanks everyone, been excited to try one of these things.