US Patent 10183406 Thumb stud including tritium

A thumb stud for a folding knife assembly includes a body extending between a first end and a second end. A hollow passage extends between the ends, and a tritium vial is disposed within the hollow passage and extends between the first and second ends. A first lens is disposed within the hollow passage adjacent the first end and a second lens is disposed within the hollow passage adjacent the second end. The first and second lenses encapsulate the tritium vial within the hollow passage of the body and allow illumination produced by the tritium vial to be viewable through the first and second lenses to illuminate the thumb stud. In an alternative arrangement, the tritium vial can be replaced with a wafer which houses the tritium vial. In this arrangement, a pair of wafers are each disposed adjacent respective lenses at respective ends of the body.