The Black Eagle 18/64" Spartan Screw In Brass Insert Weight 50 Dozen 79 is a durable brass insert designed to fit Spartan carbon shafts. Weighing 50 grains, this insert is engineered to match screw-in 5/16 field points, providing optimal performance and reliability. Easy to install, the Spartan Screw In Brass Insert ensures a secure fit and enhances the overall durability of your arrows. Ideal for hunters and target archers seeking precision and strength, this insert is a must-have for enhancing arrow performance