The Walimex Pro 10mm T3.1 ED AS NCS CS - Sony E Fit is a manual focus, ultra-wide angle prime lens designed for APS-C mirrorless cameras with Sony E-mount. It has a focal length of 10mm and a maximum aperture of T3.1, which is equivalent to f/2.8. The lens features a weather-sealed construction and an integrated focus gear ring for compatibility with follow focus systems.