Teether Bite Stick Chewing Tube Sensory Chew Biting Aid Oral Muscle Training The Yellow Chewing Tube offers a smaller stem size for chewing and is suitable for individuals who cannot open the jaw very wide. It features a narrow stem with a 9.5mm outer diameter. The Red Chewing Tube has a slightly wider stem with a 12.7mm outer diameter. This tube is ideal for children who respond well to oral tactile stimulation or for adults with a larger jaw. The Green Chewing Tube is designed to enhance sensory input through raised dots on the shaft. The shaft has a 15mm outer diameter. The Blue Chewing Tube is intended for adolescent or adult jaw sizes. It is the largest and firmest option, suitable for adults with developmental disabilities or adolescents with autism or sensory integration challenges. Note: Chewing Tubes are not recommended for children under 7 months of age.