The Fiend Omicron sprocket CNC machined from 6mm thick 6061 aluminum with offset teeth for better chain alignment. Includes 22mm spindle adaptor. You will need to get a 19mm top hat adaptor if you have cranks with a 19mm spindle. Available in 25 or 28T in black or gold. Weight: 453g. NOTE: We always fitting getting a new chain when you buy a new sprocket, for smooth running.