There are 25 bulbs and 25 sockets per string lights and 1 extra bulb for replacement. C9 is the type of bulb, and E12 is the type of socket. C9 light string, UL Listed String Lights for Outdoor, Indoor, Halloween, Christmas, Garden, Camper, Wedding, Party, Market, Porch, Gazebos, Patio, Pergolas, Decks, City Rooftops, Bistro, Backyard Holiday Decor. Note : The distance between two bulbs is 12 inches. Specifications Bulb information? Source Type: Incandescent Lamp Bulb Shape: C9 Bulb Quantity: 26 bulbs(1 Spare) Bulb Height: 2.86 inch Bulb Life Span: 2,000 Hours Bulb Color: Red White Color Temperature: 2200K Dimmable: NO Material of Bulb Housing: Glass Bulb Type: C9/E17 Base, 7 Watt Wire information : Plug Type: 2-prong plug Input Voltage : AC 120V Wire Gauge: 20AWG XTW Wire Color: Green Socket Type: C9/E17 Socket Base Total Length: 25 Feet Bulb Spacing: 12 inch Plug to first bulb: 6 inch Last bulb to end plug: 6 inch Extendable: connect up to 2 strands / 432 Watts together maximum Package Includes 1 X 25 Feet Outdoor String Lights 1 X 26 7W Red White Light Bulbs(1 Spare) 1 X Spare Fuse (already installed in fuse) 1 X Instruction Manual Cautions : 1. Please turn off the power before installation. 2. Don't touch the bulb when it's working or hot. 3. Please make sure that the E17 base type of the bulb match your lamp before placing an order.