The sram 1x11 x cog expander sprocket from one up components is designed to not only extend the life but also the range of your xx1 or x01 cassette with the x cog 44t expander sprocket the cog simply replaces the 42t aluminium cog and has 8 optimized upshift points a press fit with no loose spacers and full spline width to prevent gouging damage to freehub available in black or green 44t only