Bayonet single contact, parallel pin. The 15 LEDs are located 3 on 4 sides (12) and 3 on the end, cleverly encased in a glass housing to resemble a standard bulb without the heat. Similar light output to a 10 Watt incandescent bulb. These high quality SMD LED replacement bulbs save power. Energy efficient, they last up to 50 times longer than a standard bulb. The latest SMD chip technology is used that provides the highest light output to consumption ratio available today.