Hate wearing anything on my teeth, but these form right to my teeth and i hardly notice i am wearing them. Which is a huge deal to someone like me, i hate anything in my mouth, it makes me gag usually. Good purchase and my teeth are looking brighter daily. Before and after 1 time of an express strip on my teeth for only 45 minutes. Hope you buy them and try them, they are worth all the hype i promise. And yes i smoke and drink coffee so the yellow teeth i was used too, but my teeth look amazing now 😀