Nockturnal Universal Fit Lighted Nock Strobing Red/Blue. Each Fit nock features ultra-strong impact resistant clear polycarbonate nock construction encapsulating the super-bright single LED thats activated by a patented string-activated piston-driven linear contact switch. Like all Nockturnal nocks the Fit is guaranteed to reliably activate immediately when the string is released and it can be switched off quickly and easily with the newly designed Nockturnal Nock Tool a small screwdriver or most broadhead tips via an opening in the side of the nock. With well in excess of 20 hours of lithium battery life each Nockturnal Fit weights approximately 25 grains and will remain brightly lit for plenty of time of arrow retrieval and can be easily spotted in daylight or darkness. Available in Red Green Blue Orange and White. Specifications for Nockturnal Universal Fit Lighted Nock: Manufacturer: Nockturnal Quantity: 3 Pack Fabric/Material: Polycarbonate Illumination Type: LED Features of Nockturnal Universal Fit Lighted Nock Super Strong Clear Polycarbonate Construction Available in Strobing or Non-Strobing Versions Available Colors: Red/Green Blue/Green Red/Blue Red Green Blue Orange White Fits X H S and GT Arrows 20+ Hour Battery Life 3-Pack Package Contents: Nockturnal Universal Fit Lighted Nock Nockturnal NT-310: Universal Fit Lighted Nock Strobing Red/Blue