Black cat inner tube 20/26/27.5/29er av mtb tube roadbike tube

Schrader/ AV: This is wider than a Presta valve and typically the same circumference from top to bottom. The outer wall is threaded so a cap or pump head can be inserted. The pin in the center is a spring-loaded check valve that controls airflow and pops as you unlock it. 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.