Class 1 or Class 2

I’ve been trying to find out the difference between a class1 or a class 2. I know it has something to do with it binding properties. It also seems that it might have something to do with being 17-aa or not 17-aa. Can anybody clear this up for me and give a few examples of each?

As defined by Bill Roberts and Brock Strasser,
Class I steroids work primarily by binding to
the androgen receptor (AR). Class II steroids
do not bind well to the AR, but work through
other means. According to Bill and Brock,
class I steroids include:

*testosterone (also has some class II activity)
*nandrolone (deca)
*trenbolone (fina)
*methenolone (primo)

Class II steroids include:
*methandrostenolone (dbol)
*stanozolal (winstrol)
*oxymetholone (anadrol)
*4 androstene 3, 17 diol (androsol)

This is not my info; just passing on what I've recently learned. Hope this helps.