ACS Paws M30 13 tooth X 3/32" freewheel. This is for a 30mm hub (the threaded portion where the freewheel is installed should measure 30mm). This is the small side of a flip flop hub. If your hub is only threaded on one side, you MUST MEASURE to be sure this fits - because it probably will not fit. Will work with either 3/32" or 1/8" wide chains. Color: NICKEL outer / BLACK inner