The pack of 5 13W Quad Tube fluorescent bulbs by Duracell are designed for indoor use. These bright white bulbs have a 4-pin connector and a G24Q-1 base, making them compatible with a variety of lighting fixtures. With a life span of 10,000-14,999 hours and an energy-efficient design, these bulbs provide long-lasting and cost-effective lighting. The quad tube shape and fluorescent technology ensure a bright and efficient illumination for any room in your home or garden.