The simplicity of both the design and operation is the primary reason that the Lumenok from Burt Coyote has become the most popular lighted arrow nock on the market. The Lumenok lights instantly upon release of the arrow and will stay on until the archer turns it off. With its 40 hours of continuous run time and 5 year shelf life, one Lumenok will last season after season. If you have trouble tracking your point of impact or if you want to easily track your arrow in flight, you need to give the famous Lumenok a try this season. Fit Information: S Nocks fit arrows with an inside diameter of .244" Examples include: Carbon Tech Cheetah, Beman ICS, Easton Flatline, Easton Uni-bushing, Carbon Express Maxima, Victory VForce, and many other arrows including aluminum arrows utilizing a Super Uni-bushing. X Nocks fit arrows with an inside diameter of .204"Examples include: Easton ST Axis, Beman MFX, Trophy Ridge Arrows, Carbon Impact Hot Shaft XLT GT Nocks fit arrows with an inside...