Just wanted to tell you, I have tried go smile and it's more of an on-the-go whitening...it's just a gel you can scrub on your teeth but it goes away,,you really swallow most of it...the strips are better because they sit on your teeth for 30 minutes. If you are looking for on-the-go whitening the Listerine white pen is exactly the same as Go smile just cheaper! I think it's like 5 bucks at target... I recommend using that in between nightly whitening strips. Its great for after you drink tea or coffee.