This is a standard 12-30mm vari-focal lens with auto iris. With a shorter focal length you will get a wider field of view, whereas a longer focal length allows you to zoom in more and narrows the field of view. Auto iris lens automatically adjusts to the various light situation of surroundings*.
Not sure what size lens you need? Click here for a chart to help you decide
* For this feature to work properly, the camera must be an auto-iris capable camera.