Snafu Lite 7075 Alloy Sprocket  E-mail this product to a friend -Four-axis billet CNC machined 7075 aluminum construction -Maximum ventilation and cutouts for weight savings -19mm and 22mm steel spindle spacers included -25-, 30-, 36- & 39-tooth Weights: 25t—60g (2.1 oz.) This product qualifies for quantity discount pricing.what's this?