The Nockturnal lighted arrow nock features a 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 25 grains and is made from clear plastic so the light can be seen from hundreds of yards away. Nock is activated on the shot but can be shut off via a small switch on the nock.FeaturesSuper Strong Clear Polycarbonate ConstructionFits X, H, S, and GT Arrows20+ Hour Battery Life3-Pack