12 Accunock Standard Size Nock .244"-.246" 12 S size Accunocks .244" -246" Improves Accuracy, Reduces string wear, Reduces bow vibration Inner nock drops away into the outer nock when fired allowing for a drag free arrow release EVERY SHOT! Holds to the string even when doing multiple draw cycles before a shot Acts as a silencer for your arrows. Made in the USA