The kit comes with 24 thin, flexible strips (20, 30-minute treatment strips and four 1-hour express treatments for same-day results) that conform to the shape of your teeth. Each strip is coated in a whitening gel that includes some of the same ingredients used in dental offices (i.e, PVP, PEG-8, water and hydrogen peroxide) to remove surface stains, as well as deeper ones beneath the enamel.
Reviewers on Amazon swear by them. "I bought these for my daughters, and we [used them] as directed. Even after a few days, there was a noticeable difference" one buyer on Amazon shares. "[They made our] teeth very white, and even strangers who didn’t know [us] before would comment on the brightness of [our] smile."
P.S. They're not recommended for children under 18, but other than that, you really can't go wrong with them—especially considering the cost of an in-office whitening treatment. And hey, while you're at it, you can also score some more impressive dental finds on sale below.