KENDA RUBBER TUBE 700X18/23C A/V • Schrader/ AV: Wider than a Presta valve and typically the same circumference top to bottom. They are often wrapped in rubber. The outer wall is threaded to so a cap or pump head can be inserted. The pin in the center is a spring-loaded check valve that controls airflow. Check valves are meant to allow airflow in only one direction; your Schrader-valve tube requires pressure on the inner pin to let air in.
