LED bulbs work on a set colour wavelength, so if a white led bulb is placed behind a green lens this will give off a blue-ish light ! Also a white led behind a red lens will give off a very dark red colour more like red wine ! For this reason it is important to use white leds with a white lens. Red with Red lens etc. These Led bulbs use surface mounted diodes. As a general rule led bulbs use approx 90% less power than conventional filament bulbs. Suitable for Aquasignal Series 40 Navigation lights. Offset pins for bayonet type holder.