These Philips brand 4ft 36watt linear fluorescent tubes with a G13 cap type have a diameter of 26mm. These slimline triphosphor tubes triple coating. The Philips 4ft 36w T8 Fluorescent Tube - 835 - White offers a bright and consistent lighting solution ideal for various settings, from offices to retail spaces. Its 4ft length provides extensive light coverage, ensuring an even distribution of illumination. This 36-watt fluorescent tube emits a crisp white light that enhances visibility and creates a clean, vibrant environment. With Philips' reputation for quality and longevity, this tube promises reliable performance and energy efficiency, making it an excellent choice for both residential and commercial use. Philips Master TL-D Super 80 36W - Fluorescent Lamps (36W, T8, G13, A, 103V, 0.440A)