I asked about gg4 at my cleaning shop,and he said it keeps the glass cleaner for longer,but we both agreed,why would this be beneficial?If anything,you want the glass to get dirtier,so you can warrant cleaning them.He also said that it doesnt really make any difference to the glide when you squeegee it off.So,basically,unless you want a product for your own windows,it seems products such as these are a waste of money.