Need different chainrings or looking to replace the old chainrings on your FSA K-force / SL-K crankset or FSA Powerbox power meter? The FSA SL-K Super ABS are the only chainrings to work with these cranks. This is because of the unique ABS technology. ABS is short for Asymmetric Bolt Spacing. This means the chainrings have an asymmetric fit to the crankset. This in turn makes the whole construction more rigid, optimising power transfer.