How to Choose Lighted Nocks for .204 Arrows
A lighted nock has to fit the shaft and turn on at the shot so you can watch the hit. TitleX hunting arrows are 5mm / .204. The TitleX lighted nock 6-pack is that diameter, in Bright Green, Blue, and Red. Add them on a custom dozen in the 3D custom arrow builder.
Fit the inside diameter first
.204 nocks go on .204 carbon. A loose nock walks in the string. A nock meant for a larger ID can split the shaft. TX-5, TX-23, and Mach XV all take the TitleX .204 pack. If you already shoot another .204 hunting nock and trust that switch, keep it — diameter is the spec that has to match.
Weight and FOC
A lighted nock is heavier than a standard nock. That extra mass is at the back of the arrow, so it lowers FOC a little. Hunters who weighed TitleX packs have reported grains within about a tenth of each other. If you are chasing a FOC number, weigh the finished arrow and use the FOC calculator.
The 3D builder estimates total weight and FOC with a standard nock. Lighted nocks are a cart add-on, so the on-screen FOC will not include the light until you weigh the arrow.
Color and how they work
Pick a color you can see against your woods: Bright Green, Blue, or Red. You need a light that turns on at the shot and that you can shut off in the pack. A nock that stays on in the quiver is dead by last light.
Related resources: .204 lighted nocks, 3D custom arrow builder, how to choose hunting arrows.