This is a used Canon EF 17-40mm f/4L USM lens, a professional-grade "L" series lens known for its superb build quality and versatility. It is an excellent choice for full-frame photographers and also works well as a standard zoom on APS-C cameras. This lens is a favorite among landscape, architectural, and travel photographers. Key Features: Focal Length: 17-40mm (ultra-wide on full-frame, standard zoom on crop-sensor) Aperture: Constant f/4 (maintains consistent exposure throughout the zoom range) USM (Ultrasonic Motor): Provides fast, silent, and accurate autofocus. L-Series Build: Weather-sealed construction, making it highly resistant to dust and moisture. Optical Quality: Features one Super UD element and three aspherical elements to minimize chromatic aberrations and distortions. Compatibility: Works with all Canon EOS DSLRs and 35mm film cameras. Condition: The lens appears to be in good, used condition. The red "L" series ring is intact, and the lens barrel shows normal signs of use. The front and rear glass elements appear clear, and the lens comes with rear caps.