The number (52-1) at the end of the product name is the item's serial number. This is a type of center-focus lens, with a transparent flat surface in the center and a frosted spherical surface around the periphery. The image is sharp in the center and gradually blurs towards the edges. Also, the lens barrel is telescopic, and because it allows for various photographic expressions that emphasize the subject in the center, it is also known as a portrait lens. This product has filter threads of 52mm on the camera lens side and 58mm on the front side. The product has some noticeable scratches, but most are on the periphery, so I don't think they will significantly affect the image quality. I have included sample images at the end of the product images, so please refrain from purchasing if you are concerned about the image quality.