The thumb rest attaches to the left side of the upper frame on the Hi-Capa, it is drilled and screwed into place. It creates a hard contact surface to secure your off hand thumb to further ensure a solid and stable two-hand grip.
The frame is lightweight and all metal for strength and reliability as well as maximum rigidity for a stable grip. The angle of the rest plate can be adjusted to suit your personal needs. A part like this is a common touch to add too race pistols (competition pistols).
Though the frame stays silver in color, this model is available in a variety of thumb plate color options.