Schwalbe AV7A

"The Schwalbe Standard AV7A inner tube is the ideal companion for anyone who demands high levels of reliability and durability. This inner tube is specially designed for 20 inch tires and covers the sizes from ETRTO 28/37-438/451. Thanks to its above-average airtightness, the inner tube stays inflated for longer, thus reducing the need for frequent re-inflations."
"Made from the highest quality material and with uniform wall thickness, the AV7A offers exceptional durability and stability. This outstanding quality has already proven itself millions of times over and makes it the first choice for cyclists who do not want to compromise on performance."