The 24 tooth tail pulley was produced especially for those pilots that fly with extra low headspeed or for 3D pilots that need a very high tail response for very certain manoverous like piroglobe. For all other purposes the stock 26 tooth pulley is absolutely enough for all purposes. (i[24)=5.17:1). For speedflight the 24T pulley is not allowed except you keep the headspeed below 2000 rpm. To avoid inadvertently confusion with the 26 tooth pulley the washer shims are anodized red.