EF- Mount Adapter allows for EF lenses to be mounted perfectly on for -mount med-format cameras. It is with inbuilt electronic contacts and the bayonets are made of metal with plating treatment, being and sturdy. It also features AF function. Firmware can be upgraded by a USB port. Gold-plated electronic contact, Auto-focus function Built-in metal electronic contact, precise focus It can realize AF,adjustable aperture from camera body to lens's aperture More metal material Compatible for all the EF-lens Specification Model: EF- adapter mount Compatible lenses:for EF / EF-S series lenses Compatible cameras:for -mount med-format cameras Focus mode: Auto focus Firmware upgrade: USB upgrade port Diameter and Length: 79mm x 24mm Weight: . 80 g(excluding cap) Colour: black Material: metal Package Contents: 1 x EF- Adapter Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.