Precision vane spacing receiver upgrade for Bitzenburger fletching jig! Regardless of your preferred vane configuration, the Bitz knob will ensure consistent vane spacing. All three-vane indexing options match the original receiver. (120°, 90°, & 75°x105°). In addition to the incredibly accurate vane location, the Bitz Knob uses a wedge design that forces the nock down into the same location every time with a specific thickness to allow for positive nock engagement whether you are using target or hunting nocks. For those who chose to repair 1 vane at a time, the Bitz Knob also features a set screw that allows the nock feature to rotate inside the body for single vane repair alignment without the need to rotate your nock.