This is the awesome quality thick 450/525x20/21 Blockley inner tube, made from thye best tube material butyl, with the nickel plated metal valve stem. The metal stem was latterly always used for more arduous conditions and races, whereas in prewar times the rubber stem did not exist . . .

A thick and robust inner tube sized 450/525x20/21 made from our own Blockley tooling, made from Butyl material, so keep the air in and avoid constant pumping up. These tubes are the best quality that is possible to produce, which is why we made them, as we need uncompromised wholesome tubes to supply with the Blockley tyres that we produce. All tubes originally had metal stems until the advent of the rubber valve stem. Don't forget to fit good quality Blockley rim bands on your wheels too, to protect the tube from teh spoke heads.