OK Helical usually starts at 6 degree's and goes up to 11 degree's, lw or rw. Its a spiral( curl )way the fletching clamp makes the vane or feather take set at an angle. An offset is nothing more than taking either end of vane or feather and move it left or right 2 degrees and uses a straight clamp. A circle has 360 degrees, you maybe able to get as much as 4 degrees total offset! From 0 to 8 degrees is all you would would ever need on an arrow fer CB at its useable range 0 to 35 yds.