Dear , you buy is 4pcs Adult Dental Tooth Orthodontic Appliance Trainer Alignment Braces Mouthpiece 100% New and High Qualit Factory Outlet The ideal dental arch track, moderate forces. Without repeated visits. Patients can take on and off by themselves. Short treatment cycle and never rebounded. Avoid the trouble and inconvenience causing by Arch wire training, especially for man who cannot achieve Arch wire training. No harm to the teeth and oral soft tissue. Note: -Tooth orthodontic is a long process, please be patient for the effect. -The product is made of medical plastic and there is a little plastic smell odor, please rinse with saline or toothpaste before using.