You are probably having heard about those made by HCA that weigh 5.5 gr/inch. You have to watch things a bit. I've only ever seen one set (dozen) of these arrows and I was not impressed with the strightness at all. Some had total runout in excess of .020", meaning the straightness was about .010". Sickening if you ask me.

The other thing you have to be aware of is that using thes shafts it would be very easy to be shooting much less than the 5 gr/lb minimum recommendation for most bows. Just be aware of it.

If you're interested in the Gold Tip Ultralites there is a window on their website where you can configure the arrow of your choice and see what the total weight, FOC, etc would be. On their home page click on "Products" then "Build Your Own Arrow".