Designed to fit Edgewood, Edgewood Classic, Serrano & Bayside Estate Lighted Address Plaques. This item includes 4 LED bulbs Important Instructions: Note that these LED bulbs operate best between 18v – 20v maximum. When installing bulbs into white sockets on the mounting plate make sure bulb fits snugly between the 4 copper prongs on the inside of the white socket. If bulbs do not light up immediately you may need to wiggle the bulbs around slightly or pull out slightly on them to make sue they are making full contact with the copper prongs. Disconnect the power and check inside the white socket, if copper prongs are bent then you need to open them up so LED bulb fits between the copper prongs and makes full contact.