Carbon express wolverine bolts. 8.8 mm od. Remove all fletching. Glue insert and put in tip with oring seal. Pull knock out. Polish sand the knock end to a nice rounded edge for fitting down the barrel. Glue in another insert in knock end. Make sure metal from insert isnt overlapping rounded edge. Screw in .35 cal bore cleaner tip in knock end for gas seal... Now have .35 cal arrows for like 10 bucks. Only limit is length of arrow. But same process works for just about any crossbow bolt. If having accuracy issue tie a few pieces of yarn through the metal at the end of bore cleaner like generic fletching. Pic with red circle shows where to thread string through for fletching if needed. I dont use fletching on mine. But i also only use a 15 inch arrow so.