Usualy are equiped with spare light. Coastal light marks parts of coast, pasess, channels, harbours approaches and navigatioanal obstacles. Light carrier is usually post with gallery, placed on cylindric, coned, or fourangled tower. Harbour's light denotes entrance in the harbour and accost banks. Light carrier is usually post with bar or tower with post and gallery.
Light marks define position and borders of navigationals obstacles and sailing routes.
They can be floating, fixed or stabed, or joint elastic. As result of currents and waves, they can be moved or teared away from position. Aero light is intended mostly for air traffic and is pointed upwards. Aeronautical light serves for both nautical and air traffic. Usually, range of that light is greater than other nautical lights.