broke some fletching needed more so instead of buying some i made them. has an 8mm opening that fits snugly around my 7mm arrow shafts. I will be trying different vane types, twists, styles, ect and posting them here as well as larger and smaller cylinder types I've tested these at 65lb draw weight from 40 yards and they are fairly accurate with a small amount of tail whip, which I'm working on reducing this in design, but overall arrows stay on target photo added. printed a draft resolution glow in the dark fletching..turned out great UPDATE! I opened the cylinder to 8.5mm to allow for a easier fit and installed glue ports so the fletching can be super glued to the arrow shaft if needed just like the Outer Limits Blood Vane is set up. I incorporated this update into a completely new file that will need to be downloaded instead of the original file. If the original file works for you that is awesome but for those that may have printed the original and ran into fitting issues the new file should hopefully take care of it. Any issues can be noted in the comments section and i can work on them as a whole or as an individual basis as needed. thank you for the likes and downloads, this is my first creation and its exciting.can print with no supports, depending on your printer i recommend printing it vertically with the larger section of the vanes up.