Designed to fit most carbon shafts with a 0.166" inner diameter, the Flex Fletch LIT Lighted Nocks offer enhanced visibility and performance for serious archers. These super bright blue lighted nocks feature an external on/off switch for tool-free use, automatic activation upon shot release, and can remain lit for up to 48 hours. With a lightweight design of just 16 grains, these nocks help track arrows while preserving arrow integrity, making them a smart and cost-effective solution for the range or the field.