Replacement chain for your Brompton. This chain is 98 total links. You'll want this length if your Brompton is a 1-speed with a -7% gear reduction, a 3-speed with standard gearing, a 6-speed with a -12% gearing reduction, or a 2-speed with a -19% gearing reduction (in other words, your Brompton has either a 50 tooth front chainring with one sprocket in the rear [a 12 or 13 tooth], or a 44 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.