easy-to-use can get good effect.Typle: T4KSuit for: 5-15 year old Since first being introduced in 1992, the Pre-Orthodontic Trainer for Kids (T4K) has become one of the most popular and successful product available from MRC. The T4K is most effective in early mixed dentition for tooth eruption guidance and correction of myofunctional habits. The T4K must be worn for 1 hour each day and overnight while sleeping and always remember to follow these few simple steps:• Lips together - at all times except when speaking.• Breathe through the nose - to assist the development of the upper and lower jaws, and to achieve the correct bite.• No lip activity when swallowing - which allows the front teeth to develop correctly. Trainer Systems are designed to actively retrain the mode of the tongue and the peri-oral muscles of the mouth, correct breathing habits and align the anterior dentition. With mixed dentition, this greatly assists with both dental and facial development. The Trainer for Kids / Pre-Orthodontic TRAINER is most effective in early mixed dentition for the correction of myofunctional habits and tooth eruption guidance. Tooth Channels and Bows guide the developing dentition into correct alignment, while the Tongue Tag and Lip Bumpers treat myofunctional habits.