A good thickness robust Blockley butyl inner tube sized 450/525x20/21 made from our own Blockley tooling, so we can supply a wholesome uncompromised quality tube to fit the tyres that we produce. Nothing you can buy is anything like this good.  

This Blockley tube is thick, made from butyl and has the rubber valve stem. There is no better tube made, or available, than this Blockley tube.  We made this tube only because we needed a perfect quality tube to supply with the Blockley tyres we produce. Dont forget to use rim bands too . . .

We also have this tube available with a nickel plated metal stem.