The PixelWhip fiber head comes standard with a curl, however some folks might want their fibers straight instead.
If you'd like to straighten your PixelWhip fibers, here's how:
https://buyfiberflies.com/blogs/fiberflies-news/diy-fiberhead-tutorial-straighten-your-fiberoptics
Hope that helps, and if you have any questions please feel free to contact us!