Innovation and attention to detail at Horton goes far beyondjust crossbows and arrows. Engineers at Hortonhave precision tuned inserts to ensure that your bow andarrow work together for optimized accuracy. Precisionweight inserts dramatically impact the FOC of an arrowby accounting for such a significant portion of weight incomparison to the overall arrow design. Horton recognizesthat crossbow hunters may want to continue to finetune or customize their equipment so Horton now offerssix different weight inserts in order to achieve the recommendedFOC of 17-23% and maintain maximum downrangekinetic energy, precision accuracy, and deadly arrowpenetration! (Brass inserts fit .300" ID carbon shaftswhile aluminum inserts fit .304" ID aluminum shafts.) 6pack.