260px|Rivinletto Light on Kaasanmatala rock at the mouth of Kiiminkijoki in Haukipudas, Finland is a typical sector light beacon.Example of a sector light. The ship is navigating in the safe sector (white light is commonly marked as yellow in nautical charts). Sectors of colored glass (or plastic) are placed in the lanterns of these lights. The light will then show these colors when observed certain bearings. Bearings referring to a sector are given in degrees true  as observed from sea. Though the colors of the light will change, the characteristics will not. The change of color is not abrupt. The transition is made through an arc of uncertainty of 2° or greater.
Sector light at Botveskär on the approach to Kapellskär, SwedenExample of a sector light. The ship is navigating in the safe sector (white light is commonly marked as yellow in nautical charts). Sectors of colored glass (or plastic) are placed in the lanterns of these lights. The light will then show these colors when observed certain bearings. Bearings referring to a sector are given in degrees true , as observed from sea. Though the colors of the light will change, the characteristics will not. The change of color is not abrupt. The transition is made through an arc of uncertainty of 2° or greater.
R
260px|Rivinletto Light on Kaasanmatala rock at the mouth of Kiiminkijoki in Haukipudas, Finland is a typical sector light beacon.Example
Sector light at Botveskär on the approach to Kapellskär, SwedenExample
A
,