This is the superb 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 (ie not some multisized tube made for 19" wheels as sold with the classic tyre wholesalers experts) and made from Butyl material, which means they keep the air in, avoiding the need for constant pumping up porous inner tubes. These iBlockley Superior nner 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.