Micro Diameter meets Massive Durability. 12 x bare arrow shafts. 4.2mm / .166 ID Micro diameter shafts coupled with our DEFENDER outsert system, provides increased penetration and unmatched durability for your arrow setup. The Micro diameter, 4.2mm (ID) shaft has less wind drift in flight, resulting in improved accuracy compared to SD shafts. *Nocks and Aluminium Outserts Included