Description:Celebrity hollywood whites hollywood whites at-home bleaching trays are the perfect in-home teeth whitening system. ultra thin trays are comfortable and easy to use. high-quality, 21% carbamide peroxide whitens your teeth, with noticeable results.How often to use?For most people, completing a 5 gel kit within the first 1 or 2 weeks will give noticeable results. Any additional desired whitening effect can be maintained with "Periodic Touch Ups."How long will the results last?Your teeth will stay noticeably whiter for up to a year, however, variables like your age, diet, and individual tooth structure will affect the results.