This is the awesome quality thick 450/525x20/21 Blockley inner tube, made from the 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 valve stem did not exist . . .

A thick and robust inner tube sized 450/525x20/21 made from our own Blockley tooling to the highest quality possible, sized correctly and made from Butyl material, which means they keep the air in, avoiding the need for constant pumping up leaky porous inner tubes. These inner 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 the spoke heads.