Lightweight, dependable and highly visible, with a shot-activated switch that won't turn off until reset by the archer. Made of clear plastic, the Nockturnal Lighted Arrow S provides maximum light transmission and can be seen for hundreds of yards. The breakthrough design weighs 25% to 50% less than other lighted nocks. Installation requires no glue or magnets. Battery lasts up to 20 hours. Fits standard carbon and super-uni aluminum arrows such as Beman ICS, Easton, Carbon Express, PSE, Carbon Tech, Victory and Carbon Impact.