Replacement chain for your Brompton. This chain is 100 total links. You'll want this length if your Brompton is a 2-speed with a -7% gear reduction or a 6-speed with standard gearing (in other words, your Brompton has a 50 tooth front chainring and two sprockets in the rear: either a 16 tooth/12 tooth combo, a 16t/13t, or a 15t/13t).
All Bromptons made after December 2011 come with 3/32" chains. This chain is a 3/32" chain. If your bike predates 2011, you'll need a 1/8" chain.