Genuine Brompton Replacement JIS Cartridge Bottom Bracket. This is a direct replacement for the bottom bracket fitted as standard on all Brompton bikes since 2013, with the Spider crankset with replacement chainring. With daily use, expect to get 2-3 years out of one of these between replacements.   
 
This bottom bracket is only compatible with the Brompton Spider Crank. The previous generation Stronglight crank with the integrated chainring used an ISO bottom bracket which is no longer available. If you have a previous generation crank and need a new BB, then you will also need to upgrade to a Spider crank. 
 
Brompton Bottom Bracket - Cartridge
Genuine Brompton Replacement Component
JIS Taper Cartride Bottom Bracket
Suitable for the Brompton Spider Cranks with replaceable chainring
Durable, hard-wearing semi-sealed cartridge bottom bracket with square tapered spindle
68X119mm
Installed using a standard 22 tooth Shimano Bottom Bracket tool