How to differentiate defensive and offensive blade?

Hi Alois and Jeff,

Can you tell me how to differentiate defensive blade and offensive blade? Because some blade doesn't state it out.

Thanks~ 

Hi Byron,

You would need to try them out with similar rubbers on them and then see which is faster.  The offensive blades will be faster and the defensive blades slower.

Other than this, it is difficult to tell the difference just by looking at them.