Editing Arrow (section)

==== GPI rating ====
The weight of an arrow shaft can be expressed in GPI ([[Grain (unit)|grains]] per [[inch]]).<ref>GPI explained by [http://www.huntersfriend.com/carbon_arrows/whatsthis3.htm an arrow vendor] (referred to from [https://www.huntersfriend.com/carbon-arrow-mass-speed-kinetic-energy-research-guide.html their listing of carbon arrows])</ref> The length of a shaft in [[inch]]es multiplied by its GPI rating gives the weight of the shaft in grains. For example, a shaft that is {{convert|30|inch}} long and has a GPI of 9.5 weighs {{convert|285|gr|g|0|abbr=off|lk=out}}. This does not include the other elements of a finished arrow, so a complete arrow will be heavier than the shaft alone.