Identification bracelet

Identification bracelets were an accessory worn by certain Starfleet officers in the 23rd Century. (TOS Comic: "The Planet of No Return")

An Enterprise crewmember, Hunt, was wearing one during his final mission, at which point he was turned into a plant. It was this bracelet that allowed his fellow crewmembers to identify him. (TOS Comic: "The Planet of No Return")