From what I've read

Porous hair needs protein, fine hair needs protein. If you take one of your shed hairs and pull on it, if it stretches and doesn't bounce back, it is too elastic and it needs protein.

If it breaks instead of stretching much, it is not elastic enough, and it has too much protein. If your hair is straw like you have too much protein.

2c/3a-M-ii porous, good elasticity, APL, dark brown with a silver lining. Biggest enemy: frizz!