Teether Bite Stick Chewing Tube Sensory Chew Biting Aid Oral Muscle Training Tool. The Yellow Chewing Tube has a narrow stem with 9.5mm outer diameter, designed for individuals with limited jaw opening. The Red Chewing Tube features a slightly wider stem with 12.7mm outer diameter, suitable for children receptive to oral tactile input or adults with larger jaw size. The Green Chewing Tube includes raised dots on the shaft to enhance sensory feedback, with a 15mm outer diameter stem. The Blue Chewing Tube is the largest and firmest option, intended for adolescents or adults with larger jaw capacity. This tube may be beneficial for adolescents with autism or sensory integration challenges and adults with developmental disabilities. Chewing Tubes are not recommended for children under 7 months of age.