SmileDirectClub aligners are a competitor of traditional braces and clear alignment companies like Invisalign. The Invisalign Express 10, which uses 10 aligners, was introduced in 2005. An Invisalign Express 5 version, which uses 5 aligners, was introduced in 2012. Align Technology is a manufacturer of 3D digital scanners and clear aligners used in orthodontics. Clear aligners are an alternative to braces, but insufficient evidence exists to determine their effectiveness. Clear aligners are comfortable, invisible and easy to clean. Before steppers, wafers were exposed by mask aligners, that pattern the entire wafer at once. More attachments can make the aligners less aesthetically pleasing. As clear aligners are made from plastic, they can be warped by hot liquids. Alignment can be performed using a variety of short-read aligners such as BWA and Bowtie. Clear aligners have undergone changes, making assessment of effectiveness difficult. SmileDirectClub produces 3D-printed clear aligners. A list of currently available high-throughput sequence aligners is maintained by the EBI. Anywhere from six to forty-eight aligners may be needed. These files are generated as output by short read aligners like BWA.