Nockturnal X Lighted Nocks for Slim Arrows with Half Outs or Hidden Inserts feature a string-activated linear switch located deep inside the nock, so it can't fail. Clear plastic for super visibilitycan be seen hundreds of yards away. Weighs 25-50% less than other lighted nocks. Nockturnal X models fit all slim arrows with half outs or hidden inserts such as Easton Axis and Full Metal Jacket, Beman MFX, Trophy Ridge, Carbon Impact HOT and Easton ACC with X-UNI bushing. String-activated linear switch is located deep inside the nock Clear plastic for super visibility Can be seen hundreds of yards away Weighs 25-50% less than other lighted nocks Nockturnal X models fit all slim arrows with half outs or hidden insertsSee the Nockturnal Size Chart