bullet point: Automatically lighted after shoot,you do not need use hand to light it first! Fits all arrows with inside diameter 6.2mm carbon shafts. Constructed of a super tough polycarbonate material with a press-in-fit design. Their double-snap throat with special string angle compensation keeps arrows on the bowstring,even at extreme angles and with string loops. Insert the nock into shaft,align it to your desired position and you're ready to shoot. Description: The nock has a string activated linear switch that is housed within the nock and will not turn on or off accidentally. Battery (non-replaceable) last over 24-48 hours(battery included) After arrow retrieval simply push back activator switch located in side of nock to the off. Material: ABS Length: 6.20mm Package included: 1 x Arrow nocks(battery included) 1 x Screwdriver Note: Due to the different monitor and light effect,the actual color maybe a slight different from the picture color. Please allow 1-2cm differs due to manual measurement. Their double-snap throat with special string angle compensation keeps arrows on the bowstring,even at extreme angles and with string loops. Insert the nock into shaft,align it to your desired position and you're ready to shoot.