Service: 8 hours email reply, 30 days refund and 12 months warranty for quality. Please contact the seller if you have any problems. Widely Applications: They can not only help you adjust different types of misaligned jaw, such as:overbite, underbite, openbite, crossbite, but also help you close the gap between your teeth, or correct the gap between front upper and lower teeth when biting down. How to Use: Fix the dental rubber band on the braces, through external force to promote tooth movement, increase traction and change the periodontal structure, achieve the corrective effect and enhance orthodontic effect.(Please follow the orthodontist’s instructions to choose the size). What Can You Get: 500 pcs orthodontic braces rubber bands with 3/8" size,4.5 Oz heavy force,5 pcs orthodontic rubber bands placers are also come with,enough quantities provide for you to use. High Quality Material: This orthodontic rubber band is made of high-quality natural rubber, effective elasticity prevent them not easy to break, safe and hygienic.