The Nockturnal lighted arrow nock features a new trigger switch that is much more reliable and much more durable than other lighted arrow nocks. The switch is protected deep within the throat of the nock preventing is from being activated or deactivated inadvertently. This nock is much lighter than other lighted arrow nocks, weighing in at just 20 grains and is made from clear plastic so the light can be seen from hundreds of yards away. Fit: S Nocks fit arrows with an inside diameter of .244" (6.5 mm) Examples include: Carbon Tech Cheetah, Beman ICS, Easton Flatline, Easton Uni-bushing, Carbon Express Maxima, Carbon Express Mayhem, Victory VForce, and many other arrows including aluminum arrows utilizing a Super Uni-bushing. X Nocks fit arrows with an inside diameter of .204" (5mm) Examples include: Easton ST Axis, Easton Full Metal Jacket, Beman MFX, Trophy Ridge Arrows, Carbon Impact Hot Shaft XLT G Nocks fit arrows with an inside diameter of .165" (4mm) Examp...