High-quality 50mm prime lens made by Schneider-Kreuznach, with a maximum aperture of f/4. - Brand: Schneider-Kreuznach - Model: Durst Componon 50mm f/4 - Serial Number: 11580963 - Focal Length: 50mm - Maximum Aperture: f/4 This is a German lens. Please judge the condition based on the photos, as I cannot answer questions. The aperture functions. Please consider this as junk. Thank you for looking.