The Nockturnal Shift Lighted Nocks use a bowstring-activated linear switch with a piston-driven assembly to reliably turn on the LED at the shot. Built from clear polycarbonate, each nock includes a streamlined, tool-free on/off switch and runs on long-life lithium power. This Nock Shift model includes Universal FIT collars in a 3-pack. Battery life is 17+ hours, with non-shift G Series options offered in multiple colors.