Don't know anything about lenses but this seems in great condition. If you have any questions about it let me know and I will do my best to answer. Thank you for looking

The Aetna Rokunar No 173355E 1:2:5 lens is a standard lens with a focal length of 105mm and a maximum aperture of f/2.5. It is designed for manual focus and features a brand name of Aetna. This lens is suitable for photography with a focus on capturing detailed close-up shots with a shallow depth of field. Perfect for any photographer looking for a versatile and high-quality lens for their camera setup.