Will my Forearm get bigger by this?

No. If you want your forearms to get bigger you need to get stronger. To get stronger you have to lift weights regularly. I have found a product that helps strengthen my grip which overall has made my strength go through the roof, it's called Fatgripz, a href="http://fatgripz.com" rel="nofollow"http://fatgripz.com/a and it has been the best investment I have made in a long time. Give them a try, you will definitely see a difference in your strength in just a few weeks of regular training.