There are several options available when selecting the optimal LED light source and housing for a panel indicator. The LED can be any color, and feature through-hole technology. Most panel indicators are single color but bi-color panel indicators are also widely available. The most common bi-color panel indicators feature two LEDs in green and red, and when both are energized, allow for color mixing to display yellow to show relevant indication messaging. The LEDs can also be either two- or three-leaded with an individual lead for each LED. LEDs used in panel indicators range from 3mm to 20mm in size and typically have a viewing angle of 60° though viewing angles from 10° to 120° can also be used depending on application requirements. An optional lens can be added for enhanced visual performance. The LED housing is designed to match the panel or user-interface panel where it will be installed for aesthetic purposes. Available materials for panel indicator housing include plastic, chrome, black anodized and rubber.