These days the standard bulbs with screw fittings are being replaced more and more by the double ended lamps. As the name already tells, the double ended lamp has 2 sockets and thus double installation in the fixture. Double Ended lamps generate approximately 10% to 30% more and better light for the plants, which use it for their growth. Because these lamps also last longer they are more efficient and therefore worth the investment. Double Ended lamps do require a compatible fixture and ballast.