Jiexi Hwyp Archery Hunting Compound Bow Plastic Arrow Nocks for 5/16" Arrows Pack of 50 (black) Go to amazon.com Related posts Check expert advices for arrow nocks? Featurematerial: plasticweight: 0.6ginner dimater: 7.9mmfor outter diameter 5/16 arrowsPackage: 50 pieces per package DescriptionDescription: material: plastic weight: 0.6g inner dimater: 7.9mm Length:2.3cm size:5/16 for outter diameter 5/16 arrows Package: 50 pieces per package