The Brompton Crankset 50T in Black is a replacement set with left and right-hand crank, including chainring and chainguard, as found on all post-2013 Brompton Bikes.
A standard 3 or 6-speed Brompton comes with a 50-tooth front chain ring.
A standard 1 or 2-speed Brompton comes with a 54-tooth front chain ring - changing to 50 teeth will decrease the gearing by approx 7%.
The Bottom bracket is NOT included - If upgrading from the old fixed crankset then you will also need to change the bottom bracket (the old one was ISO standard and the new one is JIS standard).

Q100453