This is a 24-105mm F4 Art SIGMA standard zoom lens. It's for the Nikon F mount. The autofocus works without any problems. There is some dust inside the lens, but no mold. The image quality is good. A Kenko ZXII pl filter, which I was using, is also included. I'm selling this because I'm switching to the Z mount. This is a used item, so please understand that it's sold as-is (no returns, no refunds, no exchanges).