X4 Unibody Cog Set 4 cogs 11/13/17/21t for Brompton 2/6 speed wheelset (MiniMODs)
2S->4S or 6S->12S Stock Brompton Wheelset Reused No need to Change2S->4S or 6S->12S Stock Brompton Wheelset Reused No need to Change2S->4S or 6S->12S Stock Brompton Wheelset Reused No need to Change