Bohning Tower Fletching Jig Helix. Includes 3 sets of arms - Straight (Up to 4 vane) 1 degree offset (Up to 4 vane) and 3 degree right helical (Up to 2.25 vanes). Center posts for standard carbon F nock A nock HE nock pin nock and crossbow bolts are also included. Two different clamping rings accept any size arrow shaft. Package Contents: Bohning Tower Fletching Jig Bohning 12962: Tower Fletching Jig Helix